Forgetting Torah

The Midrash says:

?’ ???? ??? ?? ?????? ?? ???? ???? ??? ???? ?????, ???? ???? ??? ?’ ???? ???? ???? ????? ??”? ???? ?????? ??? ??? ???? ????? ????? ??? ??? ??? ???? ??? ???? ??? ????? ????? ???? ??? ???? ????? ?????? ??????? ??? ??? ????? ?? ????? ?? ???? ??? ???? ???? ??? ???? ?????? ???? ???? ????? ???? ?? ???? ????? ????

http://hebrewbooks.org/pdfpager.aspx?req=37460&st=&pgnum=215&hilite=

R’ Yitzchak is clearly advancing the view that forgetfulness in regards to Torah is a good thing. His reasoning is that it causes more learning. Now I could understand how back when the corpus of Torah was much smaller, it would be theoretically possible for someone to finish it in 2-3 years and then stop learning. But with the current size of the corpus of Torah this does not seem to be probable or even possible. One could learn nonstop from birth to death and not exhaust all the seforim that have been written. Would it not then be much better to retain all of one’s Torah knowledge and therefore not have to spend time reviewing, which would free up time to actually learn all the other parts of Torah? I mean, just between the Rashba and the Radvaz you have more than 6500 teshuvos (assuming my calculation are correct)! To put that in perspective, if you could completely grasp the entirety of each teshuva in 10 minutes (on average), it would take you approximately 45 days of learning 24 hours a day in order to finish. For a yeshiva guy learning 12 hours a day it would take 3 months. For a stam Jew learning 3 hours a day it would take a year. It would take an entire year for a regular guy just to get through the teshuvos of the Rashba and the Radvaz. Now add to that the hundreds, if not thousands, of other Shu”t seforim, each containing hundreds of teshuvos. As you can see, it will take you quite a while to run out of new things to learn. And that’s just looking at Shu”t. There’s also Tanach with hundreds of commentaries, Shas with hundreds of commentaries, halacha seforim with their multitudes of commentaries, mussar, machshava, chassidus etc. So it is hard to imagine forgetfulness being beneficial.

Perhaps one could answer that the Midrash is saying that without forgetfulness you wouldn’t relearn the things you already learned and would therefore never get a deeper understanding. But on the flipside, remembering everything would make it a lot easier to get a deeper understanding.