I wonder about "letting go the stick" and letting the glider recover
itself - is this really being taught as a procedure?

I have not done this in glider but it works just great in a Super
Decathelon. Even a fully developed spin recovers quicky but you do add
opposite rudder. My acro instructor (placed 10th in the 2004 World
Advanced Aerobatic Championship in Sweden, FWIW) claims that most
reasonably stable aircraft will recover in this fashion. The ones that
don't are the Pitts's and Extra's - designed for acro and nothing else.
I intend to try it in an L23 when the season starts up again.

Tony V.