There's one truth about me that pretty much tells you everything you need to know:
I truly, deeply, genuinely enjoy writing up my semester's schedules.
I love inputing all the course due dates into my calendar, and I get a teeny, tiny thrill whenever I get my various courses' assignments to align (which takes just a little more manipulation than, say....getting all the planets to align).
But here is something that no one told me when I first started teaching. You have to put yourself before the schedule.
Rather than just think about placement of assignment due dates--what is best for the students?-- it is important to think about how and when it is best for you to be grading the assignments (or exams). The primary scheduling criterion I now consider is when will I want (and be able) to efficiently grade assignments. Do I want to be grading on the weekend? Do I really want my two different courses to generate 70+ exams at the same time? Is it best to grade over holiday breaks, or would I rather get the grading done before my days off?
Perhaps these are really obvious considerations, but I sure wish someone had told me to think about ME when I planned out my syllabi schedules!!