In some ways, being in a dangerous, exciting situation, is like hopping across a stream on rocks. Once you start, you don't stop and good luck if you have all the steps planned out in advance.
I'm for a plan, and using good tactics. I also know what happens to plans once the battle starts.
Basic skills may serve you well, and you'd better have them.
Once things start to happen, your mind is trying to survive, and not very efficient at suddenly coming up with an ingenious plan to help you shoot accurately and suddenly find skills you don't have.
Robert Boatman points that out in his book, "Living With Glocks" and states it more elequently.