Daas Torah is not infallible. There are situations in which one must follow ones own daas.
No, daas Torah is not infallible. But of course neither is mine. So how would I know when to follow daas Torah and when to follow mine?
I know you said to (ironically) ask your rebbe, but ha gufa; maybe the gedarim he’ll tell you are wrong!
What I’m getting at, of course, is that despite a gadol’s fallibility, he still has a better chance of being right than a non gadol, so why wouldn’t you avail yourself of that for important decisions?