We were taught to dry-fire practice with our "empty" service revolvers for 2 reasons. It got us used to them and the trigger control on DA firing and after thousands of dry fires and shooting, they would smooth up a bit.
Taking the side plate off and filling the cavity with pearl drops toothpaste quickened up the smoothing operation on mine and my Instructor Partner's M10's when working in corrections.
I took them both home, and did this while watching TV over 2 evenings - until I could not pull the triggers any more, then
took them apart, flushed them out and re-oiled. Man, did they EVER have nice DA pulls after that.
The design of the revolvers allows dry firing. That SA design did not.