It's really going to depend on each individual rotation... most of mine though, I was able to get my work (presentations etc) and studying done during the day. A few of them I had to do lots of reading at night that would be discussed the next day. I think one of mine I actually had to work on my presentation at home because we were too busy during the day, but that wasn't the norm. We have to take an exam at the end of each rotation, but those haven't been difficult because the exam is typically over things you've been doing all month. (so hopefully you know your stuff)