ok, you may have heard this or maybe you havent, anyhow here is a good thought:
if you have issurin, and you cant find its source, you can ascribe it to bitul torah...so what does the gra tiche this as? its your bitul torah that you cant find its source! if you shtieg in your learning, you'll find the source to your issurin
also, if you have only a half hour a day to learn what should you learn? musser...because youll come to realize, you have much more than only a half hour a day to learn.
so there is some shtark musser for ya'll!