Med is full on, in the sense that it's more demanding than your average university degree, and exactly how full-on depends on which university you go to, but studying 10 hours a day is definitely doing it wrong, assuming they didn't count class time (it's a bit cheap to say I studied 10 hours today, when 8 of those hours were spent in class). Either they're spending way too much time studying, or if they're studying 10 hours a day to cram for an exam, they should've planned their studying better.
How efficient you study has nothing to do with whether you're a genius or not - a genius that doesn't know how to study properly won't get very far in medicine; and how many hours you spend studying has nothing to do with how much you're actually understanding/remembering. It's very important to work smart - work out your own learning style and use study methods which cater to it, and use common sense - if you're having a bad day and can't focus on the material at hand, then take a break and come back later.
Speaking of learning styles, I've got a couple of links where you can take some questionnaires to start working out your learning style. (Yes, I used to work at the Student Learning Centre at Otago, it's a bit of a habit to give out these links.)
http://www.vark-learn.com/english/page.asp?p=questionnaire
Index of Learning Styles Questionnaire