I gave a short (half-hour instead of 50-minute) exam as the last in-class exam in my calculus 2 class this semester. (We also have a big final exam at the end of the term.) Student feedback afterwards was surprisingly positive — the vast majority of students said it was less, rather than more, stressful. I had been expecting it to be disastrous in various ways, but actually it worked fine. So I will consider doing it again. (It is worth noting that this segment of the class — parametric equations and vectors and vector functions — lends itself to easier exams.) The major disadvantage from my point of view was that the last 15 minutes of class was only marginally usable as lecture time.
I also used the last bit of the same class to do my official student evaluations. I am curious whether this will have an impact on my final evaluations.