I’ve coached shooters in the past that had been shooting for 4 or 5 years and had deeply ingrained bad habits, they are extremely hard to break when you’ve been doing it for so long. You can explain what they are doing wrong and get them hitting targets but as soon as they stop thinking about it the old habit takes over again without them even realizing it. They have to be constantly reminded what not to do until the bad habit leaves their head for good.
I worked with one such student for over a year, foot position was wrong, canting the gun, gun not fitting, not focusing on the target, you name, if it was detrimental to shooting well then this shooter was doing it and the bad habits ran deep! It was a struggle but one day it was as if a light switch had been turned on in their head and they went from about a 35% average on an easy course in sporting clays to a 65% average on a tough technical course. Previously they were shooting under 10 at skeet and now are shooting over 20
Those bad habits can be broken but it takes a lot of work. More importantly the student has to want to get better and is willing to listen and do what they are told.
Since I run a skeet field, and there are no coaches around, I help a lot of new shooters with the basics. Some are willing to learn, and they improve rapidly, some improve, but it takes longer, and some don't improve at all, because they simply don't make an effort to improve. We have a guy that has a shotgun that doesn't fit, that closes one eye, and that tries to aim by using the beads as sigjhts. He used to ask for help, and he told us about watching videos, in an effort to improve, but he ignores anything that he is told, contonues with the same bad habits, and hasn't improved in over two years. A long time friend , who is 5'5" and left handed was using shotguns that don't fit him and was breaking 5-6 clays out of 25, until I found him a ladies gun that fits him, and he now shoots 12-13. He doesn't get any bettet, because he still closes an eye and aims using the beads, and he absolutely will not stop, no matter what he is told. Two other shooters that started skeet in the last few years, have been receptive to advice, and have earned their 25 patches. I had 12 people from three pointing dog clubs that I shoot for, come out for a one day session, and three improved dramatically, three didn't improve at all, and the others at least showed some degree of improvement. One person shot a foot or more to the left, because her shotgun was against her shooting muffs, and not against her face, so changing to foam ear plugs brought an instant improvement. Changing to ear plugs has actually helped a few shooters. Changing guns has helped several shooters, one guy went from 15-16, to a clean round the first day, with his new Citori with adjustable comb. Most people are willing to learn, and they improve, but some have their bad habits so ingrained, that improvement just doesn't happen.