Yup. I bet very few of us have heard of Dennis Tueller. Except for close combat drills, most of our range drills are at 21 feet and greater.
Not knowing can be unfortunate on either side. As the one with the gun, it could be fatal. As the one with "just a knife", it could lead to giving up in a situation that is not hopeless.
I don't claim to be great at close combat, but I can at least hit a target at 25 feet in just under one second (not the crazy fast 0.15 to 0.25 times of competition), and I know the numbers on various encounters. The hard part is deciding to shoot in time, which pretty much means before you're being charged. If someone is in your home, uninvited, you are already in immediate danger - not that it should be phrased that way when your lawyer is explaining what happened to the police.