Hand Crank Speed


Good afternoon...
I thought it would be interesting to open a conversation about the speed of an automata hand crank.
My question focuses on the 'cranker'.  What is a comfortable cranking speed for the person doing the cranking?  Is the cranking speed even important?
My answers to my question would be: Approx 90 rpm is a comfortable cranking speed...and yes, it is important.
I've built automata that have had a slow cranking speed...I found them uncomfortable to crank.  And I've built automata that have required a high cranking speed.  These were both uncomfortable and tiring to crank.  And on the automata that had a slow crank became too easy for a visiting cranker to crank too fast and cause the automata to go too fast.
What crank speed do you design for?
-Jim Coffee-