GM Yermolinsky - What it takes to be a complete 1.d4 player - QGD - Vd4

Opening: D59: QGD; Tartakower (Tartakower–Makogonov–Bondarevsky) System 8.cxd5

Player(s): Lputian, Agapov, Goldin, Yermolinsky

It is no secret that chess players, from the club level to 2700 Grandmasters, put a lot of emphasis on studying openings. The question is, how to do it right?
A good 80% of books on the market have always been opening monographs, and the newfangled source "Chessable" is likely to exceed that number. Lots of big names in its stable of authors. The product offered is a "complete opening repertoire," essentially made of examples of high-profile games decorated by computer evaluations.
While I cannot deny such works a certain degree of usefulness, mainly when it comes to helping already established players further advance their opening knowledge, I doubt they can serve as a good starting point in obtaining said opening repertoire.
I have long been advocating a different approach to the problem. Instead of studying opening moves, one should study the resulting middlegame (and sometimes, even endgame) positions, at least at the initial stages.
What to play on the first move is not an easy question to answer. Some self-searching can help one choose wisely. A typical 1.e4 player values the initiative above everything else and is ready to go after the enemy king's first chance.
A 1.d4 guy is a different animal. His values lie in a better pawn structure, and he is mentally prepared to spend the first 15-20 moves "defending," which in reality means thwarting Black's wild attempts at much-needed counterplay.
In due time I plan to show some examples of such play when we get to the Benkos and the Benonis, but a proper way to start is to address the most classical defense of them all, the Queen's Gambit Declined.

Teacher's library (691) D59 Lputian Agapov Goldin Yermolinsky opening