Lkwdfellow, we could change the school cutoff dates so that boys would start school a half year earlier.
But this stuff about boys coming back at 23 instead 22.5: first of all, the boys of a certain school year will be spread out over about 12 – 15 months (I include the extra 3 because – horrors! – there are parents who keep their kids BACK if they are within a few months of the deadline.) so some will be 23. Second, with the girls, they have no choice about seminary. They MUST go the year after high school. Boys in E”Y varies, from when a set chevra in each yeshiva goes. So the boys have a little more choice but honestly, many are at the the mercy of their chevra. You can’t necessarily propose them going earlier. I know in my sons’ yeshiva, they need to get to a certain point to fully appreciate a certain shiur.
But this is all about when the boys GO. Their coming back CAN’T be at an arbitrary cut off date if they are to get the most out of their experience. This whole system is built around the boys’ learning. Don’t we want to maximize it and build the best bnei Torah we can? Agitating for boys to come back from E”Y at an arbitrary date is absurd.