I tapped 20 4-40 holes today, .200 deep, 7 turns on the crank in the lathe spindle, tap held in the tailstock. I was thrilled that I didn't leave the tap (or part of it) in any of the holes. I think I hit bottom twice, Saw the tap start to twist. Love those spiral flute taps.
I used to tap 0-80 holes quite often. Everytime I did I was scared. Luckily I never did break my one & only 0-80 tap which is unbelieveable to me but just thinking about it now I have that scared feeling again.