BH,
“Reb Berel were the roshie yeshiva”
While you are somehow correct about Brisker Rav in Brisk, but in Jerusalem he had what we call “Talmidim” that is more than just passing thru a Yeshiva, those are truly talmidim in all aspects of life, not ONLY how to deliver a shiur, they were molded by Brisker Rav how to think and learn in all aspects of yehadus, halcha, and learning.
Mainly, as the Brisker rav would repeat in the name of Rav Chaim (who told it to Rav Baruch Ber): Vos NIT Tzu Zugen”/ what NOT to say”!
Rav Berel had a full fledged Yeshiva when he passed away, in fact, many (or most) of today’s older Rosh Yeshivos of America learnt by him..