Its Time wrote “Rabbi Yaakov Kamenetsky, Explained that one already years ago He said that always was the custom of full time elevated Scholars It wasn’t meant to be imitated by lay people or youth though”
“Full time elevated scholars” like the Rashbi and his disciples are completely pottur from tefillah! But I guess these Litvak Yeshivas think they are “part way” to the madgreiga of “toraso umnoso”, there whole life is spent every minute learning, so no time to waste on a proper mincha, unless of course they are shaving – for that avoda there is plenty of time!