[T-Bird45]

"In police training they have an “assailant” come at you with a rubber knife from about 20 yards away while you hold your pistol out in front of yourself."

It's called the Tueller Drill and the distance is 20 FEET, NOT YARDS.

[Covenantor]

Here're the specifics of the Tueller Drill.

"The Tueller Drill is a self-defense training exercise to prepare against a short-range knife attack when armed only with a holstered handgun. Sergeant Dennis Tueller, of the Salt Lake City, Utah Police Department wondered how quickly an attacker with a knife could cover 21 feet (6.4 m), so he timed volunteers as they raced to stab the target. He determined that it could be done in 1.5 seconds