“And it’s something that many R”Y would like to see changed for numerous reasons” (AZ)
Evidently there are also many who wouldn’t. I know of a R”Y who likes his boys to stay in his beis medrash as long as they’re growing. (Most will go on to E”Y.) If that means till they’re 22, and they stay in E”Y long enough to be learning well and form good relationships, not coming home at an arbitrary cut off date… Well, I don’t see total compliance.