On my second 3 hr stint of super quick poses (one and a half minutes, up to 3min poses) I determined to be a bit more assertive earlier on with my lines.
Rather than lightly plotting my main lines/masses carefully and faintly and then running out of time before I could attempt a contour line of any worth, I thought I'd minimize the planning and try and get those lines in before the timer ran out!
Instead of letter size, I'm working on 11"x17" paper as well, which I like better.
I think I'm heading in the right direction (at least for my current choice of medium, a prismacolor pencil). Here's my favorites (out of the 50-ish drawings I made).