The below video is of Lochlann Davies in his first ever squat session with a barbell.
For a first time squat this is pretty solid technique. This is only the start of week 7 of his training too which is good going.
Now we didn't start with box squats or quarter squats into half squats to reach full squats, we have just been working hard on all his weaknesses through general preparatory type work or assistance work, whatever you like to call it.
I see it far too often that strength coaches try to talk their athletes through how to squat while they are doing it. You can only take in so much and have the ability to adjust, and as a beginner you have even less ability to do so. Also if they are unable to get into certain positions then no matter how much you talk, they aren't physically able to get there anyway. This is why I prefer to spend more time on strengthen the muscles need to get into a better position than to try and talk them through it.
It is best to be patient and set them up for a lifetime of lifting then to try and rush into big lifts and injure them. The goal is to increase performance on the field.
What I see at most rugby league clubs is far from optimal. You need to know how to design an efficient program and not waste time on rubbish. I see a lot of band stuff and all this prehab type work but if you know what you are doing you can kill two birds with one stone and save the kids a lot of time and set them up for better performances.