something i've also learned over the years is that the amount of pressure that we apply isnt the most important factor of tamping.
technically tamping is the simple act of applying even pressure to the bed of coffee producing a level surface. i find that it is no longer necessary (for me) to apply as much force as i used to back in the day when i would practically stand on my tip toes to apply as much force as i possibly could while tamping. that's what the grinder adjustment is for- simply adjust the grind finer.....and if we think about it- this is how some people (the Italians, is it?) can get by with using no tamper at all!
i apply a gentle force, lift, press down again quickly, polish and remove tamper.
no longer are my wrists forced with that 50 plus pounds of pressure each and every drink.
...now some people prefer to apply as much physical pressure as possible - and that's fine too, i suppose.....IF there is a logical reason for doing so.
kind of like tapping the side of the pf. are we doing these things out of habit or necessity?
in other words, are we doing these things because it's imbedded in our heads, because that's how we've always done it or does our practice truly affect the taste of the beverage that we are preparing in a positive way?
I've been doing this for years and spent some time on some really busy bars, it's never been a problem. As far as I've been able to gather it's from improper body mechanics during the tamp. Instead of using your arm muscles to deliver the pressure during the tamp try using your arm as a piston and let your body apply the force. It's sort of hard to explain but it's helped everyone I know thats ever had the problem.