The reason for all that practice is so you don't miss.
The reason for spending some time thinking about the "what ifs" of this very sort of situation is so you have some chance to control your emotions--so you don't miss.
Some people are born with "coolness under fire"; some acquire it, and others never, ever get there. Nobody ever said it was easy--nor do I. Somehow, you just have to create a mindset of "high speed boredom", behaving as though the Bad Guy is nothing more than a moving target at an IPSC or IDPA match. Do I have it? Can I do it? I don't know. But I practice and I think about "What if?"
In that parking lot, of course, it's real life, and the only trophy that counts is 1st place--you win, you survive.
(Bill Joprdan said it all in his book, "No Second Place Winner".)
Good (censored) luck...