So this time we had a sort of "set list", and broke everything down into short poses and long poses with a timer, going strictly by the list. I recommend this approach. It maximizes the time since less time is spent deciding what the length of the pose is going to be, or when the break is supposed to be over.
So this is a 5 minute pose:
A 20 minute pose (probably my favorite drawing of the night):
And the long pose, about an hour and a half.
I try not to waste time on drawing the chair he's sitting in or any other details in the room, just concentrating on the figure. Again this one is a little stiff, but it's got some nice tone in it.