It's sometimes difficult to convince one's students that essays really do have to come in at the required length. As I try to explain, I don't arrive at the stipulated number of pages by consulting the Magic 8-Ball. If I ask for three pages, five pages, or eight pages in response to a given prompt, it's because that's how many pages it will take for a student at Level X to answer that prompt in the fullest sense. It's not because I think those page numbers are equivalent to the Holy Grail, or something of the sort. The same goes for essay questions on examinations, which I normally expect to be about three bluebook pages long--again, because that's how long it will take to develop the argument and supply sufficient evidence. I'm perfectly happy to be wishy-washy, at least to a certain extent; a paper that comes in half-a-page shorter or longer than what I requested will usually do fine (although longer isn't better...), but I've yet to see a paper one or two pages short that fully dealt with the prompt. Usually, those papers stop dead at the end, or don't have a recognizable ending, or don't spend enough time working with the quotations, or don't have any quotations (sigh).
Yes, I am grading papers. Why do you ask?