Don't worry about what other people are doing. If it's working for you, keep doing it. There were a few times I got nervous about my study habits, because I wasn't going to class or re-writing my notes or preparing for Step 1 as an M1, etc. If it works for you, then DO IT. Once I realized that my study habits were great for me, I relaxed a lot. I got the grades I was comfortable with, and I didn't study more than I had to.
Basically, my technique was to read the notes, highlight only the information that was new to me, annotate the margins as little as possible but enough to reinforce critical learning points, read the textbook as needed to clarify a difficult point, and then re-read all my notes, repeatedly. (Endlessly) That was pretty much it. I would study in a place with minimal distractions (definitely not at home), no laptop to waste my time, listen to my iPod, and take breaks when I wasn't being productive. If you're zoning out, go surf the net, call a friend, read a magazine, play pool in the student lounge, etc. There's no point in staring at a book if you're not remembering a darn thing.
You'll have study days that are completely unproductive. That'll happen. I would just cut my losses and go home (this was not too common, mind you) .
