I am facing a very similar problem with designing a complete repertoire. I don't think the best solution is strictly following a narrow repertoire, as inevitably there will be certain positions that will not be appropriate in specific playing conditions. I am beginning to think of the development of my repertoire in terms of several systems that are each appropriate to different circumstances or types of opponent. For me, it difficult to narrow myself to one mode of opening systems, as a I have a broad interest. (From your postal play, it seems that you have a broad interest also.) Here's an example of a framework of systems I have considered. You could think of each system as like a "gear" of a car, where lower gears are appropriate for lower speeds and higher gears for higher speeds. (Though don't draw too many conclusions from the comparsion!
)
Gear 1:
White: (1.d4) Trompovsky (a Prie style repertoire)
Black: Scandinavian, a6 Slav
Here each opening has a stylistic and structural similarity, and is efficient from the perspective of preparation and energy exerted over the board. Of course, there are several drawbacks to playing this exclusively. In some lines it might be difficult to beat weaker players, and against stronger players there are likely to be some "holes" in preparation due the improvisational nature of the openings. I think this should be viewed as a back-up weapon that combines solidity with a small element of surpise.
Gear 2:
White: (1.e4) Rublevsky style; i.e. many of the lines Collins recommends his repertoire book (c3 Sicilian, Scotch, Panov-Botvinnik, Advance French)
Black: Alekhine, Dutch Systems
In my opinion, the white repertoire is forceful from the white perspective and is excellent for efficiently beating weaker opposition. The black systems are more ambitious than Gear 1, and likely offer better winning chances against weaker opposition. In this system, it is very important to develop your own theory (especially as black).
The Gear 2 black openings carry a degree of risk, so it is good to a have a solid backup with the Gear 1 openings. The Gear 2 white openings sometimes have the drawback of being too forceful, so it is sometimes good to have a system that is more improvisational to generate winning chances against well-prepared opposition.
"Higher gear" opening systems (i.e. main line openings) may be developed with postal play and independent analysis, and may at some point be used interchangeably with the lower gears:
Gear 3:
White: 1.d4 (Positional, Palliser style as in "Play d4")
Black: Najdorf, Nimzo, X 2
The white systems can be adopted at an early stage with Gear 1, especially against 1...d5.
Gear 4:
White: 1.e4 (main line, as in the Anand repertoire by Khalifman)
Black: Scheveningen Najdorf, KID, Benoni
Gear 3 complements Gear 1, and Gear 4 complements Gear 2.
What is "White: (1.d4) Trompovsky (a Prie style repertoire)"? What does Prie reconmend in the tromp (I am really looking into it these days to help cut down on the study time and I like the positions)? Just wondering what his reconmendations are. Thanks.