Being able to center punch the 10 ring on a target is good, but being able to do it under pressure is what you need to be able to do in a self-defense situation.
Unfortunately, most people only find out if they can do it while stressed at the worst possible time—during a life and death struggle. Of course, there aren’t many ways of implementing stress into a training session, but it is possible.
While you can add some pressure to your shooting through competitions, such as IDPA, IPSC and even cowboy action, another way to have a partner time your string at the range. This can be done with a stopwatch, but a shot timer is better and more accurate, and can be picked up for a little over a $100. Trying to beat a known time increases pressure, especially if competing against said partner.
The pressure of competing is good and can increase your skills, but you can amp it up even with the human voice. Having your partner stand behind you and scream instructions, orders or anything that comes to mind puts you into a stress mode like few other things.
I call this a stress drill, and I got the idea from a story told by one of my NRA instructors. His range was often used by the local police for training. During a back up malfunction drill, one of the officers dropped his service handgun, drew his back up and started firing. On the second shot, the gun malfunctioned. Rather than manipulate the gun, the officer went into a low ready position to wait out the string. The officer running the drill got behind him and started screaming get it done continuously. By the time the officer was able to get his handgun back in working mode and fire, he was practically crying from the stress.
It made me realize that the human voice is one of the best stress-inducing tools for making the situation as real as possible, and I implement it as often as possible into training. Try it and let me know if it works for you.