Who does? In the olden days a scholar might take 20 years to write his or her treatise. But that's when the total number of books in the world could fit inside the Titanic. Now you have three papers to write by Friday, a Hoya soccer game to attend on Wednesday, and ballroom dance lessons Thursday which you are not going to miss because Mr./Ms. Right will be there!
If you choose to spend your time so as to leave too little for writing, then I have little advice to give you. You should accept the possibility that you will get a lower grade rather than risking plagiarism and a life-changing sanction such as Notation of Academic Dishonesty on your permanent transcript. If you are unable to get the papers done, you can always try the age-old remedy of asking for an extension. Many professors will be sympathetic, and believe me, if it comes to a choice between plagiarizing, turning in really poor work, or humbling yourself a little to explain to your professor what is happening, the third course is the best. Perhaps he or she will tell you that no extension will be given, and perhaps you will get a lower grade on that assignment. But that's still not as bad as a sanction.
A lot of professors really want you to succeed and may be willing to give you a break. You see, they want the same thing that you do: to see you become an excellent thinker. When you don't turn in your own work or work that represents good effort on your part, you rob the professor of the chance to do what he or she does for a living. Is it any wonder that professors get angry when students don't turn their work in on time or present hastily constructed, sloppy work?
So if you don't have time to do it right, shouldn't you be asking yourself the question: what are you doing in college anyway?