It is very easy to sit at one's computer and Monday Morning Quarterback. The truth of the matter is that all the practice in the world will not tell you how you are going to react when the real thing happens. We can only hope the training kicks in for when the adrenaline starts pumping and the realization comes that someone is indeed trying to kill you, you better hope that you have prepared and have a game plan by playing the 'what if' game until you are dreaming about it.
I could not tell you how many actual gun battles I have been in while in Vietnam. I thought I was prepared but the first couple of times was a real challenge to maintain any type of cool, never mind figure out tactics. Repetition of basically the same stuff until it becomes as common as tying your shoelaces was survival in high gear. Still, you have to remain sharp, cool, and rehearsed or you may not survive and you had better hope if you have a partner, he/she has done their homework.
In the civilian world, I got caught in a gunfight without a gun. Only my tactics and ability to think under fire (thank you Vietnam) barely kept me alive until the Calvary arrived. Lesson learned: never be without a gun, in or out of your home.
May the Schwartz Be With You.