There are a few classes that I would be out of my mind to miss, while there are others where everything is in the notes and there is no point in going. It is really up to you to figure out which ones are helpful for you and which aren't.
My roommate is a first year med student and I spend more time studying than she does.
I need to spend about 3x as much time studying than I did in undergrad just to PASS all my classes. I spend about 2 hrs/week watching TV (Grey's Anatomy and House MD are must-see for me) I go out about twice a month. And I am involved in 3 student organizations (in one of which I hold a position.) Apart from that the rest of my time is spent in the library.