This "acceptable self defense range of 7 yards" business is coming from some misinformed instructors.
The idea of "7 yards" comes from the Tueller drill, where it was found that in the time it took the average officer to draw and put a round on target, a BG could close a 21ft gap.
In other words, even a guy with a knife is a threat at 7 yards, to most people who have a holstered gun.
Consider that pistol duels used to be fought at 20 paces...
If somebody is threatening me in a manner that makes me worry about life and limb, and has a weapon that is inside its apparent range, I could not care less about "7 yards."
And if a guy has an edged or impact weapon at or inside 7 yards, I should have gun in hand.