Thanks, cafeIKE. I had a feeling that was EXACTLY what you meant and am delighted to learn that it was.
I've often wondered about those points but never knew anyone else who did. For example, my Rocky grinder has a "hard" zero that is right at the zero mark on the grinder adjustment. But its "soft" zero is approximately two adjustment steps up from that. I.e. at three adjustment steps I hear no noise at all when the burrs are rotating. At two, a gentle "tick tick." At one, more. At zero, I can't turn it down any more.
I am currently grinding my espresso at two-three clicks above soft zero, four to five clicks above hard zero FWIW.
Grinders are one of the keys to exceptional espresso. Discuss them here.
So by your testing, I should get to run around 220 lbs of coffee through my Junior before I need to change to new burrs. That should take me about 4 yrs with proper maintenance and cleaning. What should a set of burrs go for, may get a set now instead of waiting 4 yrs when they would cost more.