I notice that, quite often, exams have a rule similar to this:
You may not leave the exam theater during the first ten minutes and last ten minutes of the exam.
I'm wondering what the purpose of this rule is. In the first ten minutes presumably nobody would have finished the exam, but I don't see why that should stop anyone from leaving. As for the last ten minutes, if I had to guess, it's to prevent an "arms race" where examinees race to leave before everyone else so they can avoid the traffic jam at the end of the exam. However this hardly seems like a deal-breaker. There're also exams where nobody can leave the exam theater until the exam is over, and usually the end of those exams aren't a complete mess: examinees just wait until scripts are collected and then leave. Besides, having this rule just pushes the "arms race" to ten minutes before the official end.
What is the point of this rule?