Your on-call schedule depends on the clerkship and your team, every 3-4 days or not at all depending on how the rotation is set-up. So in short, yeah, it's like residency for whatever amount of time you're on the service. Call can be long, it depends on how fast you are when it comes to getting your pre-rounding and scut out of the way in the beginning and when your attending rounds the following day. You'll at the very least get 1 day off a week, but then again it depends on your team and service, my personal worst was 14 straight days on internal until a day off. Different hospitals have different call schedules, some have a night float which means a team/resident dedicated to only working nights for a specified time. Anyway you cut it, you kiss sitting on your ass from 8a-3p and free weekends goodbye when you hit the wards.