I'll start off by giving a student perspective. I learned basic firearm safety and marksmanship in Boy Scouts back in the '80s.
I don't recall if BSA taught Coopers 4, but I do remember the emphasis on keeping guns pointed in safe directions, and NEVER point a gun, loaded or not, at another person.
Many years later, I decide to get a gun for self defense, stumble onto INGO, and read a 4 vs 3 debate.
I'm now an adult, with a healthy respect for Firearms, and the potentially lethal consequences of mis-handling them, and my first thought on reading Cooper's rule #1 is "No it isn't."
I don't know if my reaction is typical, but I'm sure it happens often. I just don't understand why an instructor would want the first and most important interaction with a student to be a provably false statement.
enough from me for now. Commence discussion.