The key is to not cower and back up. Move laterally and then laterally again moving around them in an elliptical (orbiting) manner. You can see in the article in the pics of the 3 guys in the parking lot how much peripheral vision ONE step opens up.....it is NOT something that takes an olympic athlete to do.
If you have a spouse with you grab her and put her behind you. Same with the kid. Unfortunately there just really are not any techniques that...
A. Work for EVERYONE
B. Work in EVERY situation
C. Require you to do NOTHING
MOST folks are going to see you moving out from in front of them and suddenly remember they are late for an appointment somewhere else. And if they DON'T..then you have just bettered your position.
Lets take your "woman in heels" situation...is that more difficult to step off to 3 and then to 3 again and then to 3 again?? Yes I suppose. It is also gonna be pretty difficult to FIGHT in those heels if a guy comes up behind her and grabs her while she's talking to the first guy. So what are we going to do? I agree 100% with using reflective surfaces. Use 'em if ya got 'em. But they are not always available. So then what?
Turn your head? Try it with a training partner. His instructions are to attack you as soon as you turn your head. See how exponentially more difficult that is to prevent the sucker punch from landing or the tackle when your head is turned.
Again, this stuff works.For EVERYONE. Period.
Is it EASIER if you are physically fit? Yes. But then again, so is walking up and down stairs, walking the dog, painting the house and walking to the fridge to get a sandwich. EVERYTHING is easier if you are more fit. But unless you are on crutches it is not difficult to take 2 or 3 steps so you can see what was previously behind you.
Give it a try....it will make sense when you actually do it.