You'll get the whole spectrum depending on your school, your rotation, your residents/staff, and your own personal level of interest. Some rotations are inherently more lecture-oriented (I remember one day on Medicine we had 5 hours of lecture), while stuff like surgery and OB can be more work-oriented.
Just to give you one example, I'm currently on my general surgery month. We M3s get there around 5:00, round on our 3-5 pts and do notes, hopefully before our respective intern arrives. We round with the upper level resident at 7:00 and start cases at 7:30. We alternate between afternoon clinic and formal attending rounds in the afternoons, usually leaving for home around 4:00. We take call q8 with another student, typically tag along with the intern on floor calls and ER trauma cases for awhile. If we're not busy around midnight they'll let us get some sleep, but occasionally it's one big damn 32 hour shift (we meet back up with our respective teams in the am and are allowed to leave by 1p). We have a few lectures/conferences a week and/or a quiz or two, and there's always reading. We usually have a weekend day off, sometimes two, so the workweek averages out to 60-70hrs.
By contrast, I had a 2-week surgery elective rotation with ENT just before Christmas, during which time we arrived at 8:00 for clinic/OR, and I never left the hospital later than 3p. No floor notes, no formal rounds, no lectures, time between pts for lunch. My resident was a PGY-5 with a big-money job already lined up so he liked to stand back and teach, letting me do way more than any 3rd year should in the OR and in the clinic procedure room. Awesome.
