Going To The Beis Midrash

The Targum Yonason says at the beginning of the parsha that Moshe went to the beis midrash.  Why did Moshe decide now that he must go to the beis midrash?  The Lev Simcha explains since Moshe at that time lost his supernal wisdom (Rashi,) therefore he had to go learn to rediscover his wisdom.  Where did the Targum see in the verse that he went to the beis midrash?  The answer is that if you are not told Moshe is elsewhere you can assume he is in the beis midrash.  I heard a similar idea from Rav Avrohom Shmulevitz in regard to Yaakov Avenu.  Chazal derive from the calculation of Yishmoel’s age that there are 14 unaccounted for years of Yakov’s life.  Chazal say those years he spent learning in yeshivas Shem Ve’Aver.  How do Chazal know where for those 14 years?  We see from here that the assumption is that a talmud chachom is learning.  Therefore, if were Yaakov went wasn’t identified one can safely assume it was to the beis midrash.