In my classroom, students do a lot of formal writing. In an effort to respect different processes and paces, I allow my students to have somewhat open-ended deadlines (the final deadline being the portfolio presentation at the end of the semester). I do give suggested due dates and if they don't have a certain amount of writing done each marking period, they recieve a failing grade on the progress report. Those who do not turn in the papers by the suggested due date still have the opportunity to finish the work for the portfolio with no penalty.
Now, without getting into a discussion of accepting late work (that was already done here and here), how much time do we give students to write their papers. It seems to me that they take as much time as is given to them. I see little progress on the papers until a week prior to the deadline. That doesn't mean that they aren't working on them at home - many do. But, for many of my students, the deadline is the only impetus to actually do the work - they don't want to get a failing grade on a progress report.
So, do I give students a few weeks to do a paper - with multiple drafts, conferences with me, and peer reviews? Or, if they only do the work in a week anyway, why don't I just give them a week to do it? For the next paper (which is the character analysis paper), I'm going to give them significantly less time to complete the assignment (for the suggested due date, at least - they will still be able to do it in time for their portfolio) and see what happens.