The thing he didn't mention is will-power / the ability to focus / capacity for thinking. I think the vast majority of students fail to pay attention in class,

The thing he didn't mention is will-power / the ability to focus / capacity for thinking. I think the vast majority of students fail to pay attention in class, but even when they do, they fail to think hard about the concepts being presented. I see it in myself, when trying to grapple with a new concept, it's so easy to say to yourself 'just give up' and turn your attention elsewhere. Especially since you can tell yourself that your diverting your attention to something equally valuable (eg. reading the next page of the book, or listening to the next part of the lecture). It's easy to mentally pat-yourself-on-the-back for doing X hours of studying, much harder to confront your cognitive limits by trying to integrate a new concept on the spot (as opposed to picking it up gradually through practice and experience). Another thing to note though is that if you develop the self-discipline to hit the library for hours on end every day, that self-discipline will arguably serve you better in life than the A-A+ average you might have gained with better study techniques.