Here's the problem: while I have some liberty in designing the test, I am preparing the students for a final examination and so far I've found it easiest to choose questions and time limits from previous IB final exams.
The students, of course, hate the extreme time pressure. I don't like it either. When at university, my exams were 5 hours long and 6 questions large. Sometimes I left after 1 hour, sometimes after 5 hours, and more often than not I was able to use that extra amount of time available to dig deep enough in memory to find what I needed. Sometimes I re-derived formulas and above all, the type of thinking I engaged in during the extra hours was a good learning experience and added to my understanding of the topics.
So on one hand I'm preparing students for time-pressured examinations, and want to give them practice in such settings. On the other hand, the exams are frustrating, very procedure-oriented, and not especially conducive to learning. At this point I'm welcoming any suggestions on how to proceed.