for a minute i was thinking it's a bit unrealistic how quick yatora gets over his funk (or at least seems to) but honestly it seems a bit more human that way. unless he's gonna get full-on depression i don't think it'd fit that well in the story for him to remain unmotivated for more than a few days.
but that said, i'm glad we're getting to the "no real hobbies" thing now, because it's really hard to actually pursue a passion if you don't have a more casual one to spend time on on the side. i'm kind of hoping the theme sticks around because it'd be a shame to develop a whole interest for yatora and then just never bring it up again