Going back to earlier in the thread, way back when I was a boy we were taught (gliding) MINIMUM 30 degrees of bank for final turn.
Even through commercial training they wanted exactly 30 degrees of bank, not 20, not 31. 30!
PS. Despite much deliberate 'abuse' resulting in plenty of departures and spins, I never managed to provoke the 'difficult' spin which the Firefly is known tp possess.