Honestly, natural ability goes a long way. There are people that are talented and hard workers, though. I may be wrong (I guess it is possible I will get straight Cs) but I think a lot of people waste A LOT of time during their studying. I also think people lie to themselves a little just how hard they are working (I saw a lot of self-proclaimed "gunners" at the bars last week)
TITCR. There's a limited utility to studying. If you can study efficiently, you can do in 2 hours what someone else does in 4 or 5. If you understand the concepts, you don't have to try and teach them to yourself at the last minute. And people are making a lot of really pointless charts and graphs that will be of NO usefulness on exams and taking full practice exams (at 3+ hours each) and writing out full answers.
Besides, there's no real way to know how you will do in comparison to the other students at your school
until you get your exams back.