There may be someone who can come on and either shoot me down in flames or corroberate my understanding of the situation at at most clubs. Squad players train Monday Tuesday Thursday and Friday. Wednesday and Sunday (unless there are matches) are days off. In Brewsters era ICT trained 90 mins in morning and same in afternoon. There are also a number of +16 year olds on the books who are able to put in similar training regimes. For all others training is two or three nights a week but does not interfere with education. Younger children usually train sat morning and play sundays, though they may also have a couple of forty five min stints during the week I would imagine ICT are similar.
That is how its done at a lower division club where friends of mine are coaches and I understand that there are rules / guidelines, partaining to this, for all clubs to follow . I've never heard of any club preventing children from participating in other sports though I do know that coaches who see potential in 14+ age group may try and discourage this as the training required for some sports can conflict with that required for football. For example sports that develop and require strength can conflict with those that require agility.
To be successful in any sport requires committment and dedication, both from the participants and the coaches, and if the lads dont want to heed the advice then they shouldnt be there. My coaching friends do there stuff on behalf of a div 3 club with ambition to progress. They do it voluntarily and unpaid and they often feel frustrated by the ones who cant be-ersed, especially if they have chosen the team on sat morning and come sun match one or two dont turn up.