I think it just depends on the person. I never study unless it's the day before (sometimes the day OF) the exam. Ever. Never, EVER study. I hate it. It's boring and I don't like doing it.
I'm one of those people who sit in class like "what the FUCK are this professor talking about?" while everyone is like "oh I understand!" and are answering questions that they ask and everything. They make 60-70% on the exams and I make a 95%.
My GPA is 3.67 cumulative, I've never studied outside of a test.
If I studied I am fully confident I could have a 4.0 GPA......but to me, it's just not worth it. I'm too lazy
I guess what I have is a gift (being able to learn 6 chapters in one night). I do know that it does take a certain amount of giftedness/skill to make good grades. I know some people that just don't "get" school. They study for HOURS upon HOURS and still make Cs and Ds.