The proper distance for "Combat" practice is an unknown. My 1913 Small Arms Firing Manual has for dismounted 15 yards and 25 yards distances for slow fire, rapid fire, and quick fire. Mounted about the same.
I assume slow fire is one minute per shot, five shots. Rapid fire was five shots, pistol at ready, 20 seconds. Target for SF and RF was an "L" target, a 6 foot by 4 foot target with a 5 inch round bullseye. Quick fire sounds fun: pistol holstered, on command 3 seconds target exposure at 15 yards, 4 seconds at 25. The target is a bobbing E target, a human silhouette 29.5" high, 15.5 inches wide.
The horse cavalry got to shoot at those targets, at the gallop. That would be fun.
NRA 2700 Bullseye shot out to 25 yards till the 1950's, when shooters were obviously cleaning the slow fire targets and it became too difficult to determine the winner. So the slow fire targets were moved out to 50 yards, the timed fire (20 seconds, five rounds, fired twice) and rapid fire (10 second, five rounds, fired twice) became the course of fire. Fifty yards is a very long way with a handgun, and if someone is fifty yards away, maybe the smart thing to do is run away, instead of exchanging bullets.
Current combat games focus on super short distances with high volumes of fire, so we see spitting distances used in training.
Pick the distance you feel comfortable