Make sure your expectations are made clear in terms of schedule. My retail rotation was at an independent pharmacy, and through email, my preceptor told me that as long as I do 40 hours/week, I could come and go as I pleased. The pharmacy was open from 9-6, so I figured I would come in at 9 and leave at 5. Everyday, I asked the preceptor (at around 5 or so) if I could take off, he would always say yeah; never gave any kind of vibe that he wanted me to stay more, or that he was disappointed or anything. Then, on my midpoint evaluation, he wrote that I was consistently leaving 1 hour before the pharmacy closed. This to me seemed disingenuous.
At another (clinical) rotation, the preceptor would have us come in the morning at round 9AM, round with the medical team until around 11 or so, then meet with him at around 1. About half the time however, he would text us maybe 30 minutes before meeting time, saying that he was running late by a couple hours, so we would have to wait; furthermore, several times, he would text us a few hours later, saying that we weren't meeting today. Not complaining, because that just meant that we had 3+ hour lunches and whatnot, but looking back, it was so much wasted time...