Big Pistons asks "Is there any part of any glider flight where you would want to deliberately enter and then recover from a spin?"
Yes, darling. EVERY FLIGHT, ACTUALLY. We have to do it before qualifying for solo flight. I used to hate and fear it, but after 1,800 hours of instructing, cross country and competition flying, I LOVE IT! So lots of us who fly gliders do indeed want to spin. When I was instructing (had to retire last April) I would demonstrate how to enter a spin and how to recover. And then ask the student to enter the spin himself, and do the recovery. From safe height and in a safe glider, of course. You cannot really appreciate the difference between a spiral dive and a spin without doing it yourself, I feel that if the instructor puts it in the spin and then asks the student to recover, the lesson has not been learned. There is a certain "whump" when the autoroation begins that is quite delightful.
So now, because a slight impairment to my vision led to me stepping down from solo as well as from instructing, I have to fly with a safety pilot - yee haw! Would you like to be my safety pilot? Only instructors need apply.
And be sure you are strapped in tightly, and gone through your HASSL checks!
PS. That's 1,800 hours in gliders, 1,200 in power, iR and seaplane rating...