John K Jordan
While doing a turning demo once I turned off that club's PM with the big switch. Then it wouldn't come back on! Someone said, oh, it does that - we never use it, just use the speed control.

I eventually got it working again. That switch that could use a quick disassembly and cleaning!

At home I use both the big switch and the speed control, depending. I always check the speed before starting. Can't remember ever being surprised.

For those who enjoy turning big, possibly out-of-balance blanks, might consider investing in a remote emergency cutoff paddle switch. Mine is mounted on a magnet and positioned so a touch with the leg stops the lathe.

JKJ