Glamdring, my thinking about shaving seconds has to do with a certain amount of "If he does this, I do that."
A simple example: Assume some hostile statement coming from a male, behind you. Options: Run, immediately, to create space. Or, turn and look over your shoulder? Stop, turn around, while putting your hand on your weapon? I think I'd haul tail for at least 10 or 20 feet, and *then* look back--still moving, and preparing to draw/fire.
If you don't create space, but turn to look or stop and look, you might well lose valuable time.
You can pre-think several "If A, then B." scenarios. *Maybe* you'll save some time in the decision-making process. The obvious caveat goes back to Clausewitz: "No battle plan survives contact with the enemy."
, Art