Any fighter – boxer, bjj, mma– that is preparing for a fight will be training for more than he is expecting in the fight. They'll train at a very uncomfortable level with bigger guys, faster guys, and for longer rounds. To have plenty of reserve in the tank to make the fight manageable in comparison.

Shooting is no different. Especially if it's defensive in nature. You should be training and practicing at a level that feels very uncomfortable. Shooting at a very aggressive pace and at uncomfortable distances. Finding out where the wheels come off and what you're actually capable of. To have plenty in reserve to compensate for the deterioration of skill under stress. Shooting slow fire accuracy and thinking that skill will transfer over to anything remotely usable under the level of stress defending your life is delusional.

Learn to run your gun. Aggressive shooting with accountability.