It won't matter in a revolver, but it can in a semi auto. As the slide slams the bullet into the chamber, it may set the bullet back a bit in the case. Do that a number of times, get the bullet far enough in the case, and you can wind up with an overpressured round.
I keep a cocked & locked 1911 on the nightstand. If I unload it for any reason, I put the chambered round in the bottom of the magazine and load a new cartridge. I also make sure to regularly shoot the ammo that's been in there so that it's all rotated.
If ye love wealth better than liberty, the tranquility of servitude better than the animating contest of freedom, go home from us in peace. We ask not your counsels or arms. Crouch down and lick the hands which feed you. May your chains set lightly upon you, and may posterity forget that ye were our countrymen. ― Samuel Adams