Even so, if the number of "errors" or "bugs" that the USP folks state they "corrected" is accurate (and I would have no reason to dispute their claims, but I'm also in no position to double check them) and using Skyrim as the guide for what to expect with FO4: there will still be scores, hundreds even of notable "errors" or bugs in the game long after Bethesda stops tweaking it.
Hell, there were major bugs that were not addressed in the USP patches, such as the dragon stalking bug, and plenty of others. It seems to be nigh on impossible for a software product this complex to be truly and completely bug free, even if it were not being run on millions of different machines by millions of different users who find millions of ways to break it.
It is ostensibly humanly impossible to achieve what some folks seem to think is reasonable to expect: a game like Fallout 4 that is completely perfect, runs perfectly with minimum infrastructure, and never experiences any errors.