This is the kind of thing I am producing at Life Drawing class. I am accustomed to working on a fairly small scale and these pieces of paper are about a metre long, so forcing me to make my movements from the shoulder, instead of from the elbow or the wrist. The model also holds each pose for only one minute, so I have to work fast too! All very good for me, I am sure.
After a number of these brief warm-up poses, our tutor takes pity on us and instructs the model to do 2 and 5 minute poses. And later still we get some 15- and 30-minute ones too. The model generally reclines on pillows for these longer ones (keeping still is much harder work than you'd imagine), and, with the heaters on and the concentrated silence in the room as we sweat over our work, she or he often falls asleep. We smile to each other as tiny snores come from the curves and angles and graduations of light in front of us (for that's all the model becomes), and pretend we didn't see if it suddenly awakens with a little jerk and snort.