Studying The Opening: Find the "Typical" Ideas
Unfortunately humans cannot study openings like computers (i.e. just play the move recommended by their opening database). It is important to study, and know, the most critical lines of the opening you are playing; but what happens when the opponent plays an unexpected move? That's the time that you hopefully know the typical ideas in the opening that you are playing.
This is also an important reason to stick to playing the same opening at least for 20 games. Many of my students see a great game in the Sicilian Dragon, and want to try it out. They then lose a game where White plays the Closed Sicilian 1. e4 c5 2. Nc3 and decide that they can't even get the Dragon all the time (darn those anti-sicilian players!). Next, they see a great win the in Marshall Gambit (1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. 0-0 Be7 6. Re1 b5 7. Bb3 0-0 8. c3 d5!?) but then lose to the King's Gambit (1. e4 e5 2. f4!?). Onto a cool idea in the Pirc/Modern (1. e4 d6 2. d4 Nf6 or g6) and so on.
While it is commendable that this student is studying chess games voraciously, it is also not ideal. Without playing and studying an opening for an acceptable amount of time (at least tournament 20 games) there is no way to learn the "typical ideas" behind the opening that they play. Let me show you what I'm talking about:
