A whole bunch of large life study drawings I made for a recent art class -- all drawn in charcoal.
Time ranged from 5 minutes to 40 minutes.
We had three models over a span of 4 days, two of which were male, and one female. The class itself was still pretty fundamental, so we had a few first-timers who looked a bit embarrassed. lol
Personally I love life study - drawing the human body is such an immense challenge in itself, and you've got such a short time to draw it, that you don't even pay attention to the fact that you've got a naked stranger sitting 6 feet away from you.
Here's the other post with my gesture drawings--
We did some super short 2 minute or less warm-ups: