Just to ramble a bit........
The main reason my Dad taught us to never dry fire a gun when I was younger was for safety reasons. He used to say "Noone ever gets shot by accident with a LOADED gun." Checking the action/chamber/magazine for shells/cartridges became a check, double-check, triple check, etc. occurrence for me.
I learned later through reading and from others that it could damage the gun, too.
Several years ago I took a Ruger Blackhawk into the shop where I bought it. It had been rebuilt into a five-shot .454. The owner's son looked it over, made sure it was not loaded, cocked it and put his thumb between the hammer so he could check the trigger job out for himself. That seemed like a good idea except I use a leather strap to catch the fall of the hammer when doing so. Seems like another way to save some wear & tear when practicing trigger control.