Good instructors, training....
The same goes to firearm instructors/teaching cadre. I'm required by state div policy to qualify once a year. I've seen a few good instructors & a lot of bad ones.
Training cadre should avoid; "war stories", personal opinions, gripes, and other meaningless remarks. New students or shooting range members can become confused, annoyed or get the wrong impression.
Many students take a "be like Daddy" mindset & wrongly assume they can shoot weapons or use tactics way beyond their skill set(s).
In 2008, I took a armed class with a veteran instructor who packed a S-A 1911a1 .45acp. Of course, 3 or 4 of the students then wanted to get 1911a1 models too! Surprise!
Bad habits or poor skill levels come from students who get in way over their heads or try to do to much to soon.