I think your problem isn't the opening. You mention "the more book moves the better" but do you understand what is going on with those moves? Just memorizing isn't going to help especially when your opponent takes you out of book.

Instead, I recommend focusing on tactics, positional play, basic endings (maybe Lucena/Philidors position at the most). GM Repertoire books pretty much assume you have a solid grasp of these things.Don't get me wrong; the series is great but seems to be quite a bit advanced for you.

eg) What use is an opening that gives you the all coveted "bishop pair" when you don't know how to play B+Ps vs. N+Ps (on both wings) endings.

IM pfren is exactly right, of course - and when you are ready to work more on openings, you probably won't start with the Grunfeld, it is very complex because it has one of the most fluid pawn structures in chess.  So you will want to try something very solid against it, either a Kingside fianchetto or the Smyslov line with 4 Nf3, 5 Bg5, 6 e3, etc. so you can get developed and avoid the wide-open lines for a while. 

Repertoire books arn't going to tell you why a position is good or bad or explain the endgame dynamics common to an opening. There is a lot more to opening prep then just memorizing some moves, afterall. If you're not ready to wrap your head around the tactics and endgames an opening strives for then most of the effort you put into studying the opening is a waste of time. Likewise, if you understand general tactics and endgames well enough to need to study openings you should be able to crush everyone at your level already.

This is really sad. A genuine IM, IM pfren, takes the time and trouble to offer his advice for free, only to be shouted down and contradicted by a bunch of 1200-1400-rated players. I think we might be better advised to listen to someone who has demonstrated that he actually knows what he's talking about.

It's like trying to do calculus without knowing how to divide, multiply, or even add.

Calculus could conciveibably be done without the ability to divide or multiply, but adding and subtracting is a must.

-1

Definition of a limit involves division, as does the rule for integration of polynomials, whereas multiplication is used in their differentiation. 

Young man, I feel that the answer to your question about why you keep losing has been amply demonstrated above. If you want some explanations at our level, have a look at http://www.eudesign.com/chessops/

As for wanting move 15/16 advice, I fear you do not understand exponential growth either...

@benonidoni,

Nothing wrong with playing a reversed black system with the white pieces, but only a few books are written for the White side specifically.

For example, Tony Kosten, "The Dynamic English" (1999).  Suggests using the Botvinik Formation against everything black can play against.  And Mihail Marin, "The English Opening" (Vol. #1, I believe).  Covers the Botvinnik in depth.  Knock yourself out.  It's a Master Level book, afterall.

But English Theory is still huge, and all the caveats and advice given above by titled players still applies.

There's a large body of knowledge around "tactics and endgames" that you must learn COLD if you are ever to get above USCF B Class.  And your zillions of games at blitz (with no corresponding increase in your overall playing strength) should have "proven" that fact to you by now.

Sorry, "boredom" is no excuse.  "Openings" are a sugar rush for weak players.

I play only 2 openings, presently.  Modern Defense with c6, and Reversed Slav (London System)...but I spend 90 percent of my study time on middlegames and endgames, plus generic "tactics and strategy."  It's the only way to improve your playing strength over time.

So get with the program.

Opening are just a "black hole" for the study time of players under USCF 2000.  But if you're content with playing blitz or bullet at USCF 1500 strength forever, so be it.

We grow too old fast, and too late smart.  

I am a little confused. How can you play grunfeld with white? Can somebody post a model line? Thanks.