IsaVulpes wrote on 08/12/18 at 11:18:52:
 
Perhaps the OP didn't start playing until he was an adult? Around here there are plenty of people who work hard at their chess but never get much above 1600 FIDE.

I've noticed that strong players often have a blind spot about this. I was once told that "anyone with a brain" could reach 2000 FIDE. He didn't mean "if they start young", either.

I'd second the recommendation for classical chess. Something like the two Ntirlis books based on answering 1.e4 with e5 and answering 1.d4 and most flank openings with d5, provide more than any 1700 player would need but do provide some explanation. The key I would stress is the room to grow. Different lines can be chosen in both 1.e4 e5 and 1.d4 d5, allowing you to experience different middlegames.

I can say a few (E: Turns out it became more than 'a few') personal words about this, as I played a repertoire consisting of
- White 1.c4 2.g3
- Pirc vs 1.e4
- KID vs 1.d4
for several years. At some point I grew bored of it and switched Openings out one by one to other systems (Kan vs 1.e4, Benko vs 1.d4, 1.e4 with simple lines), before I finally ended up going for a "full switch" to 1.e4 mainlines, 1.e4 e5 mainlines, 1.c4 e5, and the Nimzo/Ragozin complex against 1.d4.

First of all, this "one-size-fits-all-approach" is of course massively counterproductive to your chess. I started doing it when I was a ~1500, and I climbed to ~1700 in ~6 years with it. Since I did the "full switch", I got to 1900+ and am still rising fast.. in ~2 years.
It's not just the fact that you lack experience in varying structures, but there's also the notable issue that the positions are actually very difficult to understand properly: 
- If I lose in a standard open game, I can usually figure out on my own (or with the help of the computer) what went wrong where - ok, I miscalculated a line; alright, I mistimed my central break; I messed up and conducted my attack in too hurried a fashion rather than first bringing in extra material; etc
- By contrast, if I lose a game in something like the doublefianchetto.. figuring out what I did wrong tends to be an undertaking of .. colossal proportions, which in turn makes avoiding the same mistake in future games much more difficult, as everything is very subtle and often the computer itself doesn't really understand what is going on. 12.Na3 turns out to be an error because on move 18 the Knight is misplaced there, but 11.Na3 would have been excellent because then after some further maneuvering you are just in time to play 18.Nc2, which covers some concrete threat.. I just never understood what was going on anywhere.

Second of all, this approach doesn't actually work whatsoever, because while your setup might look the same every time, the play still wildly varies depending on the opponent's moves.
Black plays ..Nf6/..g6/..Bg7/..d6/..0-0/ in both the Pirc and the KID, so you might figure ok after 5 moves it's the same position from the Black side, so these must be very related, but if you then follow the Mar del Plata and compare it to the mainline Austrian Attack, it quickly becomes clear that the openings really have nothing at all to do with each other. 
The visual similarities that pop up when looking at the positions at a glance are just meaningless for actual play; the difference in the White setup throws everything overboard.
The same of course applies in even stronger fashion when compared to White openings. A key motif in the KIA is the e4-e5 push.. how often do you get to play e5-e4 in the KID? The SemiSlav is a murderous opening with some of the longest tactical sequences in chess, theory going 30 moves deep in the Botvinnik mainlines.. the Colle is just nothing.
Pawn structure and piece placement doesn't work in a vacuum, the other player's pawns and pieces are just as important as your own in determining the course of the game. 
On top of that, this will make it tremendously difficult to actually remember both ideas and concrete moves, as all positions you encounter will look vaguely-similar-but-not-quite, and whether in a specific English subvariation you were supposed to push a3-b4 or e3-d4 quickly becomes indistinguishable

Thirdly, "familiarity with structures" and whatnot is a weirdly overrated concept. How often does someone win a chessgame because they understood a deep positional idea from their endless hours of opening study, that the opponent didn't see at all? The idea that you "just study some structure a lot" and suddenly you see all these genius moves that your opponent would never come up with even though you're no better than him sounds like it comes straight out of one of those scam opening books that promise a winning advantage after 1.e4 c5 2.Nh3..
Of course people will be less familiar with the positions if they aren't critical, but.. that also means they don't need to be familiar with them to play decent moves, so it really doesn't matter!
If you play 1.b3 all your life to "learn the structure", and I open Mikhalevski 5 minutes before the game to learn the first 5 moves of 1 line, our game will go 1.b3 e5 2.Bb2 Nc6 3.e3 Nf6 4.Bb5 Bd6 .. how much great use will your 'knowledge of the structures' be now? I will be perfectly fine if I just play natural moves from here.

Fourth, as MNb mentioned, your opponents will just murder you with prep in some way or another if you are truly this inflexible. In my last tournament I got a sizeable advantage out of the opening leading to a winning attack against a 2480 IM (which is 500pts above my rating, and sadly I managed to bungle it up and lost anyway ) pretty much entirely due to prep, and there I had to look at several different lines in multiple openings.. if you really just play the same *anything* in every game, you will just lose lose lose after the first games hit the databases

Lastly, and perhaps most importantly, you say you plan to "put a lot of work" into this opening study. Now, if I take that statement 1/4 seriously, that means you will be better in the opening than roughly 99% of your opponents. Just the way it is; the majority of players are terrible at them, exiting book around move 5 and just doing random stuff that makes little sense the majority of the time.
Now, if you put a lot of work into the English, that means you get to punish your Black opponents mishandling the position a bit, which leads to you getting +== positions where you can maybe win a slightly better endgame on move 60. 
If you instead play concrete mainlines, then your opponent mishandling the position means you are +1 after 15 moves and mate them in 25.
Just a collossal waste of time to spend a lot of work on unconcrete system whatever openings that are generally chosen because they AREN'T a lot of work. The very idea of something like the Hippo is that you can blindly play the first 10 moves and never have to look at any theory; the idea to suddenly use this as a testing White try for an advantage is completely lost on me.

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If you do want to
1) Play a "universal system" where White and Black openings are thematically similar, sharing many ideas
2) Put a lot of work into your openings, to ensure you get an advantage with White and at least comfortably equalize with Black
3) Play this 'universal system' all your life
Then that works out perfectly fine!

Your universal system should be.. (drumrolls in the distance)
.. Classical Chess!!

- 1.e4/1.d4 doesn't matter, just mainlines; trying to grab space where you can and going for the e4-d4 pawncenter if permitted
- 1. ..e5 mainlines against e4, stopping White from getting the e4-d4 pawncenter, avoiding space disadvantage if possible, breaking with ..d5 when you can
- 1. ..d5 mainlines against d4, stopping White from getting the e4-d4 pawncenter, avoiding space disadvantage if possible, breaking with ..e5 or ..c5 when you can
Tada, this is:
- *Actually* similar (as in: for actual play, in terms of finding moves, rather than if someone takes a picture of your position): You fight for central control, quick development, space, and if the opponent takes a misstep you directly can go on the attack
- Worth the work! With Black you can easily take over the initiative if White plays a few poor moves, with White you can just win if Black goes wrong
- Perfectly sound at all levels of play! This repertoire truly can carry you from 800 all the way to 2800.

What a great system! Pick this up, like I did, and your rating will just soar. Good luck!
Bonus points for getting used to finding the best move on the board starting from move 1, rather than starting from move 10 after having played a bunch of autopilot whatever moves that you know are suboptimal, while ignoring your opponent's replies..

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To answer the last question: "Would I be able to get up to 2100-2300 Elo if I played exclusively a universal system?" 
.. Sure. After all, openings are just a tiny aspect of play at that level, so anything works basically. The 2480 IM that I almost beat just plays the most passive crap with Black (eg this great system named after Smyslov in the Petroff: 1.e4 e5 2.Nf3 Nf6 3.Ne4: d6 4.Nf3 Ne5: 5.Nc3 Nf6) and then expects to outplay his opponents in the slightly worse middle-/endgames that ensue.. clearly that is working out, and also a very valid approach! 
Just as a "I want to focus my work on openings"-type approach.. it's bogus.

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The main advice I can give beyond that is.. *just do stuff*.
Doesn't really matter what you do, just do something. Learn anything. Study whatever. 
You are "ready to invest a lot of time", are motivated enough to write a long post on Chesspub with ideas, but are 1700 Elo. How come?
The numbers I gave ^up there were DWZ (German national rating), which generally is ~100pts below FIDE (for me too now that I have an Elo, I just broke 1900 DWZ and am 2000 on FIDE). 1600 DWZ is a level where the people who do anything for chess are aspiring youngsters that will be 1800 in a year's time - everyone else pretty much just plays some 30 games a year and doesn't look at a chessboard beyond that.
How are you 'ready to invest a lot of time', have played for a good while ("during all my past chess life"), but still stuck at that level?
That doesn't really work out, unless 'ready to invest a lot of time' really means 'at some point in the future I will tooootally do this, but not right now', in which case really that's the core issue, and not whatever opening you pick.

Just play, and work, and have fun. Don't debate endlessly your future repertoire when you are finally a 2200, and whether you can get to FM by playing the Hippo with White.. actually sit down at the chessboard and *do stuff*. 
The rating will come by itself, no amount of work will ever be "wasted", and if you are 2200 and hitting a roadblock you can still ask if perhaps now you need to change your repertoire to get the remaining 100 Elo points.. discussing this now is truly putting the cart before the horse.

Hope this helps.

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P.S. You are currently "changing your repertoire each year", but are certain that system openings wouldn't get boring.. where do you get that confidence from? Why are you currently changing your repertoire? Just for fun? Because you end up distrusting the Najdorf, so instead you feel like the Pirc might be a better system?
Again, instead of seeking the opening system that suits your personality and future plans or whatever the best, just.. go out and play, and study whatever you like, and everything else will happen naturally.

I've toyed with the idea of a "universal" IQP repertoire, which goes roughly as follows:

1.e4;


- c3 Sicilian
- Italian, aiming for the d4 ed4 cd4 Bb4+ Bd2 line, or otherwise just playing whatever
- Either the French Tarrasch with 3...Nf6 4 Bd3/3...c5 4 c3 etc. (a la Yevseev) or the Exchange French with an early c2-c4
- The Panov Botvinnik Caro-Kann or the Pseudo-Panov (2 c4)
- Possibly 1 e4 d5 2 ed5 Nf6 3 c4!?

- The Tarrasch QGD
- The Four Knights Sicilian 

The White part of this repertoire was seen in Sam Collins' Simple Repertoire book (although this was published after I had more or less mapped out this repertoire ), and the Black part basically formed the two-book "Meeting" series that Everyman put out in the early 2000s (?).

Seems like a reasonable "universal" choice to me, as playing IQPs tends to be fairly beneficial for your chess - and importantly, there's plenty of times where you won't get one (i.e. playing Black against 1 e4 you generally won't; 1 e4 e5 with White; Pirc/Modern/Alekhine, etc.)

I'm sure that the key to improvement for a 1700 player (who if I am not mistaken said here 4 years ago that he was 1800) consists in taking up a universal opening system.

Not.

This is a sure-fire way to never improve again. 

Learn to play good moves, right from the very start of the game. Don't worry about what an opening is named or anything else, first just learn to play good moves, control the center, develop pieces, gain space, etc, etc.