Just like most chess players, I've been struggling for years to build a good repertoire.
Around 1983 when I was a novice I opened 1.e4, played the Giuoco piano and the closed Sicilian (Nc3, g3, Bg2) as my main openings (because I had an old book by Max Euwe that explained these openings really well) and against other defenses I was basically on my own.
With Black, I was lucky to find a defense that was tailor-made for me: the French. Whenever I faced this defense as White I horribly lost game after game, so I decided to follow the old adage 'if you can't beat them, join them' and chose the French as my primary defense against 1.e4.
I started studying and playing the French in 1990 and have never ever felt the need to look for another system. Against 1.d4, 1.c4 and 1.Nf3 I tried the classical Dutch (...f5, ...Nf6, ...e6. ...d6, ...Be7) with mixed results.
As I became more experienced, I made the mistake that most chess players make, switching from opening to opening, never taking the time to study any of these openings really thoroughly. I have played 1.d4 followed by 2.Nf3 (yes, the Colle, which gave me tremendous results) or 1.d4 and 2.c4.
I have also played 1.Nf3 and 1.c4, but the results were rather poor, in the sense that I drew against weak and strong players alike.
With Black, I have tried many systems: the Nimzo/Bogo/Queen's Indian complex, the King's Indian, the Queen's Gambit, the Tarrasch, the Slav and the Semi-Slav, even 1... b6.
Two years ago I decided to build a good repertoire that would last me a lifetime. This is what I came up with.
I spent considerably less time on studying other defenses (1...d5, 1...d6, 1..c6 etc.), as I don't encounter them as often as the three main systems. I spent one or two evenings on these lines and that turned out to be sufficient.
Scandinavian 1...d5 2.ed ... 2...Qd5 3.Nc3 followed by g3/Bb2/Nge2 and O-O 2...Nf6 3.Be2
That's it. I don't spend time on 1...b6 or 1...b5 or 1...Nc6
As a back-up system for white that I use every now and then when I am not in the mood for a theoretical debate (e.g. early morning games), I play the King's Indian Attack (1.Nf3, 2.g3, 3.Bg2, 4.O-O, 5.d3, 6.Nbd2, 7.e4 and now it's time to wake up and start thinking).
I always hope for 1.e4 when my instant reply is 1...e6! No problem there.
Against other moves, 1.d4, 1.c4, 1.Nf3 I've always had trouble but about a year ago I found a book on 1...d6 against everything by IM Cyrus Lakdawala. I studied the book, collected games which I analyzed, started playing 1...d6 and my results have been excellent so far. I certainly intend to keep 1...d6 on my repertoire for a while.
So, after 30 years of playing chess I've finally got a good repertoire together. These days I hardly spend time on the openings, before the game I refresh my memory and that's it.It serves me well against opponents rated 1400-2100.
One thing I learned is this: don't try to study everything! For example,after 1.e4 c5 2.Nf3, I have prepared lines against 2...d6, 2...Nc6 and 2...e6. Against other second moves by black I just go 3.c3 and see what happens. I have never bothered to study moves like 2...g6, 2...a6 or 2...Nf6.
Likewise, it is not hard to find good recommendations against off-beat stuff (1.f4, 1.g4, 1.b4 etc.), but I have never really spent time on these moves, I have met 1.f4 and 1.b4 maybe three times in a 30-year career, so it's not worth the time.
The bottom line: I don't think there is a solution that will work for everyone. All chess players have to discover which openings are good for them and that takes (a lot of) time. It took me about three decades :)
Good luck on your quest for the perfect repertoire! (perfect for YOU, that is)