Every time, because I believe in the Bullet Fairy.
LOL, I have to get me one of those (LOL.)
I have mixed feels on press checks, the only time I press check is to make sure I have a snap cap in the chamber before dry firing a pistol as well as making sure there is not a loaded round in it. (every time.)
I have had only one AD and that was 45 years ago when cleaning and recharging a Walther PPK. (finger on the trigger problem) Since then I do not keep a loaded round (only a snap cap) in a pistol that goes into the safe and have had no AD's.
When the pistol is taken out it is recharged with a fresh round and a full mag placed in the pistol. All my pistols have loaded chamber indicators so there is never a question of whether it is loaded or not. (and they do work)
Every time you do a press check is an opportunity for an accident to occur. Placing your hand in front of the barrel is not a good thing. That is why I have mixed feelings on doing them when they are not required to make sure the gun is UNLOADED. You are better off to fully rack the slide with the mag out to insure that there is NO round in the chamber and visually check.
If you have mags that are not feeding properly or you are failing to properly seat your mags, then you need to take care of those problems FIRST than to press check your firearm every time.
Stay safe and know your firearm and how it is functioning.