Keep the hammer all the way down, and you can work the set triggers. I think there is risk of damage or deformation of the gun's internals, trigger bar or sear, if you work the triggers with the hammer at half cock.
Very rarely, I'll practice one or two shots letting the hammer go from full cock, but will either put a couple of faucet washers over the nipple to absorb the blow, or, for flint, replace the flint with a wooden wedge.
If you're going to practice dryfiring regularly, and it's a worthwhile endeavor, do so w/ hammer down & uncocked.
SCL