I think the context of this discussion is important. You are stating that you don't allow obvious or known threats within a certain radius because you issue a verbal challenge that is very specific and threatening.
The ability of some people to get closer than that, people whom you have not categorized as an obvious or known threat, is what I am discussing. Examples would be entering a restroom as someone is leaving, standing in line at a convenience or drug store or gas station, or people walking by your car without saying anything as you pump gas.
I am not saying you should embrace the fact that people spend time there... but they do (unless you live a very, very unconventional lifestyle). The
TPI paradigm, which is interchangeable with Shivworks teaching and a lot of this discussion re. the "fence," is partly about doing away with black and white thinking and seeing in terms of grey, accepting that sometimes people may get close, or we may be tired and not initially see through a ruse, etc. Think of it like a layered defense system in any other context. Sometimes the initial layers won't work; I'm glad that your experience so far has been successful, but there obviously need to be "deeper" layers.
Saying "put your hands up if you think you may have to fight" is not revolutionary. Coming up with a system that takes average joes with guns who have done some basic marksmanship training, and gives them an advanced and proactive decision making paradigm with verbal and positional components, is not something that is being done very commonly.
That isn't to say no one has ever figured this stuff out for themselves - I am sure being a patrol cop is very conducive to this sort of thing. But you have to realize that this material is just not being taught commonly enough to civilian students (or many cops for that matter) especially not in such a systematic, effective format.
To me, and to most people, this
I NEVER EVER let anyone that close to me,if they try - I stop them by any means at my disposal.
Is not realistic, legal, or useful. Sorry... it just isn't. Nor is a one size fits all, black and white approach. And as much as I think it's overused, the Tueller drill is a good example of how fast someone can close distance; assume they aren't brandishing a knife or giving you a specific reason to threaten them verbally. Heck, reduce the speed by 50% and you have about 4 seconds to deal with a person approaching you from 7 yards. THAT is where material like the fence, MUC (posted by Fred), and so on, shine.