Have you tried to turn a reduction gear driven diesel engine ?
Turn off the fuel flow or cap the air for the combustion and it stops rather quickly.
It is not like a worn out radial that may ticker on for a few revolutions until all combustible material is used up.
Or was this the gasoline version of the airplane?? But even then, the IO540-K5 in our Saratoga maybe turned through maybe 9 or 12 blades when the mixture was cut.