On Monday I was the model for the portrait life drawing group at the RAL Art Center. The group meets on Mondays from 10 until noon.
It was different being on the other end of the pencil/paintbrush/charcoal stick. And it is a lot harder to sit still under a bright light and let other people look very closely and intently at your features, then one might think.
I was a model for a painting class at VCU eons ago when I was in college. It was a paying gig (this one was too, but not as high paying) but it was tougher because they would put you into odd positions which you had to hold for certain periods of time, over and over and over again… sometimes for day after day.
If you like to draw from life and you paint or draw the human figure or portraits, I think it is a good idea to be a model for other artists from time to time so you appreciate what a model must do.