Im not sure on how high schools do this but for intermediate schools i know the process since i am a PE Co-ordinator at a school in south auckland and it is alarming the skills the kids are being taught these days.
Ok this is how it goes before the term starts each year you get an outline on when school tournaments are and how many weeks you have to prep your school intil tournament time usually you get a about 6-weeks to 8 weeks depending on a number of things. So once you get the outline you are then given an assortment of session plans or training programs by the governing body of the sport you are teaching in the last two years case it was Auckland Rugby League and then your are asked to implement these into your team's sesssions every time you train so for us for when league is on training is usually 3-4 days a week for about a 1 hour and a half and man the session plans only detail attacking aspects such as passing,kicking running with ball in hand and some skills that only certain kids would know how to do (Halves) Like grubber kicks chip kicks and bombs saw nothing for defense whatso ever why would you teach a prop on how to do a correct grubber kick or a flick pass??. Also have seen in the past in training sessions about flick passes amongst other things. So what i decided to do was scrap the ARL approach of sessions and just create my own implementing all the skills needed for league. I started teaching kids the shuffling of defensive lines like the compressed defense and numbering up in tackles to many kids in my case had no idea how to or knew what numbering up in tackles was after all that last year we went from last to 2nd just by pretty much teaching the basics and fundementals
The lack of teaching kids the fundementals of the game starts from a younger age too many kids now want to be SBW or Benji or
Shaun Johnson and not want to concentrate on the little things like effective tackling,defensive reads running angles amongst other things. I think this has a lot to do with the kids coming out in NZ now you only get a few that are hard workers and know how to play solid defense alot of people think that having someone big on the edge in the centers or second row is a good defensive apporach when really if you have taught the kid nothing on reads,anticipation or effective tackling the kids from NZ are always going to struggle on defense.
The point is that kids nowadays have no desire or commitment to learn the art of playing defense and there not forced to which is a shame for me because being a effective defender is just important as being a good attacker.