I asked two refs about this and they both gave different answers as well. One thing I'm learning is that the High school rulebook isn't exactly clear but I guess that's part of the fun(frustration)
kind of a compromise
edit- I suppose of course best to catch it right away, and if a player was on briefly and not caught by the refs and then hurried off the court without interfering then perhaps let the T go.
But I think I agree with the two wrongs and you can't ignore the violation and perhaps I would call a T in cases where I know for certain the player has been on the court for a length of time where it could affect the play. Even if the player is off the court. lots of grey area there but...oh well.