This is a very interesting tread; I have been working a lot with improvements plans to try to improve, I have been stuck to a plateau around 1700-1800 for years and have been trying a lot of different approaches to break out off that level, for a long time without much success.
However the last year I suddenly have made a jump forward from about 1750 to 1910. What made the trick was to change my playing style from positional to more aggressive play. Reading "The attacking manual, vol. 1" by Jacob Aagaard and "My best games" by Karpov was the books that really gave me a kick. At the same time I also completely changed my opening repertoire to more tactical openings.
But what worked for me does not necessarily work for others.
So I guess the most important part is to try to identify weaknesses in your own play (that’s one of the reasons you need to study your own games) and find out what kind of mistakes you make, is it tactical oversights or is it bad endgame play or do not develop your pieces properly in the opening or are you playing to passive or ...?
When you know your weaknesses and you know what playing style you feel suit you, then you can make your study plan accordingly.
And study games, that is very important I think, when studying games you get the full picture and learn about all parts of the game, openings, middle games and endgames. And you don’t have to study all the side variations, only if you are curious about them. Most important is to try to understand why the moves that were played were played. And why the mistakes were mistakes.
Most important is that you have fun studying; when you have fun and study something that is interesting to you, you will learn more and remember more. So if you are reading a book and you find it boring or you get tired of it than find something else to study for a while, you can always return to the first book later if you want to. And don't focus to much about having to read a certain no. of pages every day, it is more important to focus on what you think is interesting. It can be better to use more time on a interesting game or exercise than to rush through a fixed number of pages each day to reach you target. When you are burning the midnight oil it is importent to study something that is fun and interesting to study otherwise you will quickly loose your motivation!
It could also be a good idea to read some general books like "Improve your chess now" by Tisdall or "Chess for Zebras" by Rowson to get a broader perspective and to think about how you play chess, how you use your thinking time during a game and what you should be thinking about during a game and stuff like that. It might not increase you knowledge about chess, but it might improve the way you use your knowledge!