Twice seriously.
About 1 turn in a Tucano that fell off a stall turn.
Incipient in a Spectrum that I was taking a look at for the AAIB, because we weren't quite sure about the cause of a fatal - we were reasonably certain afterwards (straight into incipient when you stalled at climb power).
The main difference to training is that it is a loss of control, to be initially treated as such, not a developed spin. I personally don't like the training regime concentration on the developed spin, which becomes effectively an aerobatic manoeuvre - all my experiences are that an inadvertent spin entry is a loss of control that can be recovered quickly before a developed spin occurs - but an opposite rudder recovery is not appropriate in this case.
G