First of all, there's always something you're supposed to be doing. If you have three assignments for a class due at the end of term, you'll definitely have more important things to get done all term, and then you won't have enough time at the end of term to do the assignments. Even if you didn't do anything fun all term, you'll have procrastinated by getting more of each of the assignments for other classes done than you would have had you worked on the end-of-term assignment earlier. It's really hard to give up on an assignment that's due tomorrow because you haven't started on the one due in two months. It's not just that you have a more immediate reward if you procrastinate the stuff that's not due tomorrow; the reward is calculated and reported to you in advance in percentage points, and you definitely lose those points if you don't go after them immediately.
Also, assignments are designed for maximizing the standard deviation, which gives the most detail for grading. This is achieved by having the average be 50. This, in turn, means that, if you're doing fine, you could do twice as much work and still not get everything done. And you could check over your answers if you really wanted to, and take even more effort. So it's not like you're ever done with all your upcoming assignments and have time to work on the long-range ones.
Also, the main risk isn't doing badly in classes or failing them, it's going insane. If you pass any of your classes (or even if you don't, really), you're better of than if you have to take a term off. So doing something fun and relaxing can actually be quite important. I heard claims that sleeping at night sometimes helps, too, but I didn't try that. Relaxing when you need to is always on a shorter deadline than the end of the term, so it takes precedence.
And, of course, every class has something or other due at the end of the term (or a final just after classes end). You're in trouble if you've got three things due for this class at the same time as every other class has some project or exam.
So the optimal strategy is probably to choose deadlines around when your other classes have big assignments and exams, and stick to those deadlines, but tell the professor you'll have everything in at the end of term (but then forget that you didn't specify your deadlines).
The thing I'd find most interesting is how many students chose to have the deadlines at the end of term, but then turned in the first assignment in the first half of the term.
Field notes from the field in question (Score:5, Interesting)