I can tell you my expectations of my 3rd years is to coming with an open mind, open heart, hunger to learn. That being said they often are following residents, helping with admissions, going to lectures and when they go home often studying to look as sharp as they can the next day. Students who are proactive and on the ball get to often assist/do more procedures and various activities that are often desired (central lines, intubations etc). Some rotations will have weekends off and some will have variable weekend requirements. some rotations may have calls requiring being in the hospital despite having worked a full day (aka when they come home they will be sleeping to catch up). Some attendings love teaching and are nurturing and some are not. There is often variability in amount of chaos going around (I'm not mean to my students but if I have a crashing patients I have no problem asking them to step a side to provide patient care). My best advice is talk to your significant other on early in the rotation because they will often have a general idea what its like. If its something like optho, derm etc, you may be correct to assume weekends are free. The other caviot is if the rotation is a place where the med student may apply for residency then they may work way harder than "expected" to earn facetime and get in good with people making the decisions on who to accept for residency. I can tell you that I notice a huge difference in med students who want to do residency at our hospital than ones who don't particularly want to, namely the amount of time they are present, level of preparedness, and initiative they take to show that they deserve to be there in 2 years. best of luck.