Yes, Gilbo3... It's called the Tuller (Tueller) drill. The only thing is, bad guys have gotten faster - so in reality it is sometimes more like 10 yards/30 feet as opposed to the old 7 yards/21 feet. At my company, we now start the drill at 30 feet and then have the knife wielding opponent move closer in 6 foot increments so that the students can gain a better understanding of just what they are up against when it comes to bad guys with edged weapons... I've been at this a while, and can clear a Blackhawk Serpa Level II holster and fire a fatal shot versus the average bad guy pretty quickly - he doesn't get his blade on me until he starts at about 7 feet if I must remain stationary. If I am allowed to move, he can be as close as 6 feet and still not get me. You have to "get off of the X" if you want to live.
Danny Inosanto is now 73 years old, and I'd feel certain that he would cover the 10 yards and shred any person before they ever knew what happened to them. Probably the fastest, most accurate knife combatant ever known.
Regards,
Raven6
good info Raven, most folks would be hard pressed to defend at even 30’...