Number and length of rotations depends on the school. NDSU makes me do 9 five week rotations. The U of MN has 8 fivers and 1 10 week (I think). I ran into a U of M student last week that said he heard some schools doing only 6 rotations (no idea how long they were, though)
The difficulty of the rotation is really site specific. Like I said posted earlier-I really got slammed to the wall on my adult med rotation. But I just finished a rotation at the corporate office of a chain pharmacy, and I got a lot of extracurricular stuff done (researched for a new car after mine was totalled). That's not to say that I didn't learn anything-I had plenty of projects to do. It was just easier to let things slide for an extra hour or two. This current rotation has me hanging out in clinical affairs at a drug company. While I have things I am expected to do, the work dries up at times. My preceptor has his job first, and when he gets time, we chat and he'll assign me some more stuff. It leaves me plenty of time, as long as I realize that deadlines have to be met. Time management anyone?
I have yet to have a bad experience on rotations. Your preceptors were once in your boat, too-and they remember it. Even with the Adult Med rotation-since I came in early, my preceptor usually tried to kick me out by 3pm-he knew I'd put in my time and more. I usually stuck around until 5 or 6, though. He knew too much that I wanted to learn. I guess I got a lot out of it because I wanted to. I had a classmate doing her general hospital rotation at the same site then-and she never hesitated to get out early. She hated the rotation, and didn't get much out of it because she didn't put much into it. I think part of the reason was that she already had a retail job lined up.
Any other questions, feel free to ask. I think the work is starting to dry up again.
