I came across this video which covers exactly what I was talking about footwork before the attack. What he talks about at the end is how to read the environment.
Two examples of a blank slate instructor and a realistic understanding of an. Had he ever been in an situation with multiple attackers or played "man on the bottom" as a kid. (kids game where boys will try to pile on top of one person, until that person can't escape or whines like a little cry baby. lol. ) Then he would know that his scenario is not realistic and the techniques that are being used aren't realistic in the context of trying to maintain your footing. You don't want your self-defense students to walk away with a lack of understanding of the reality of the dangers you refer to.
This is a better approach
The reason I show this is not to pick on the instructors but to highlight that they were probably students once and what you see is what they learned as students about self-defense.