Interesting thread for more than 1 reason.
1 It is one element of the flight envelope not often practiced even by FIs, but also the element most likely to do you damage and bite you on the ar*e if recovery is not effected properly.
2 I have heard many anecdotal stories that although there is standard spin recovery which we all demo'ed effectively during our FI training and examination there are aircraft which refuse to behave normally in terms of standard recovery- believe the RAF guys have some stories about Bulldog recovery and its not a good idea to find the aircraft you are spinning for the first time has some unexpected peculiarities-- not that any of us would go spin a new beast with a student, without some type training first!!
3 Not sure about the stresses and strains imposed on the airframe during spinning but from a structural integrity point of view, I certainly have some reservations about spinning a 40 year old airframe-and 90% of us are teaching on airframes that old- especially when you see the condition of the outside of the aircraft and wonder whether the load bearing inside conditions match !!
Always remember in my sprog PPL years, a spin demo in a Tomohawk with the intructor telling me to look over my shoulder during the spin. That empennage was twisting quite notieceably-- very unnerving!!