To be fair, this kind of complication is relatively rare in compiler work.
On the other hand, when it does come up, it does tend to create several hours-long meetings where there are more opinions on what the "obvious" semantics should be than people present. I've always been a stickler for trying to actually specify the obvious semantics to try to forestall these conversations.
Seeing how long the story of poison/undef is dragging out for LLVM, I'd say it's more of a years-long process than an hours-long one. ;) But still, the most important part is that there's a discussion at all, and the desire to properly solve this problem.
On the other hand, when it does come up, it does tend to create several hours-long meetings where there are more opinions on what the "obvious" semantics should be than people present. I've always been a stickler for trying to actually specify the obvious semantics to try to forestall these conversations.