A few others said that they had never asked their students how long they really do spend on problem sets. While some students set a time limit of a few hours for themselves after which they will stop working on a particular problem set, many students will take as much time as they need to finish, even if that means staying up all night. I talked with only three students who get most of their work done a few days before the set is due, which means that the majority of problem set work is done the night before. Accompanying this practice is often panic, for there is not enough time to call a TF, nor to find out if there is a mistake in the problem, nor to think through challenging problems. Students are geared towards finishing problem sets, even if they have too many problems.
Many students feel obligated to finish each problem assigned.
Students do not like to leave problems undone, some due to pride and some out of guilt. One student would not even turn in problem set when she could not complete it. They sometimes include extra hard problems that are not required to be completed. And yet many students lose self-confidence while agonizing over these problems. The way problem sets are graded has a large impact on the students' desires to complete the problems.