What about the bloated periods of time called Bein Hazmanim? Those are also vacations. Some Yeshivos let out the day after Purim and don’t reconvene for another month and a half (Rosh Chodesh Iyyar). Others let out on Rosh Chodesh Nissan. In Europe it would takeh take 2 weeks to get from Pinsk to Minsk. That’s why they allowed bochurim that amount of time so that they get home in time for the Sedarim. But today?! Are you kidding me?
Somehow, it’s become “poreish min hatzibbur” if any yeshiva had the Chuzpah to start back before Rosh Chodesh! Same with Rosh Chodesh Cheshvan.