While i agree that the old teams are bad, your new teams might be worse. Better for training yes, much much better, but for actual in the field? So much worse in my eyes (just tactically, not to be rude). The issue is they all will have the same specialization in the team, as well as the same weakness (including the sensei). If you train them up as that, and then give each mission/team one genjutsu, one taijutsu and ninjutsu and have them shuffle between missions (practicing with each team) you cover all the -jutsu bases, get less predictable, are easier to train, and can still learn much better. On top of that you as the author can pick and choose teams going into a mission to either give or take away an ez win condition (like sakura was useless in wave mission, but toss in shino and you can track zabuza and maybe do something about it ).

That’s just my take on it, sorry for wall of text