In my school, Surgery, IM, inpatient Peds, and Ob/Gyn were the most time-intensive. Surgery, IM, and Peds had Q4-5 overnight call (and in surgery, they pointed out that none of the ACGME rules applied to students, so instead of 30 hour call, it was more like 34-36 hours). Ob/gyn had no overnight call, but we had 12 hour days during the week, and would have to come in on one of the weekend days to round. We also had one week of nightfloat on that rotation. Basically, in 3rd year, I had to work as much as the interns worked. In FP, outpatient Peds and Psych, it was more like 40 hours a week without any call or weekends. Outside of the time spent in the hospital, we also had to read up on our patients and study for the Shelf exam (which is pretty much impossible to do during surgery).
4th year, on the other hand, is a breeze. My school only requires 3 rotations-sub-I, EM, and an Ambulatory month. I did my sub-I in IM. I was doing Q5 overnight call, working about 75-80 hours a week. EM was easier-because it is essentially shift work, I worked about 40 hours a week (although the rotating shifts messes up the sleep cycle, and in essence, gives you less free time than you thought you would have). Ambulatory medicine is a breeze; my preceptor only made me come two days a week. The rest of 4th year is at your discretion. You can make it as easy or difficult as you want. During 4th year, the only exam we had was for EM, so you don't have to study nearly as much as you do during 3rd year. You spend a good amount of your time preparing your ERAS application, interviewing, etc.
