I once got hung up for a year or more over a short story. It was science fiction, we were on another planet of Earth-type: would it have Earth-type mountains by definition, was plate tectonics a necessary condition or a likely one or likely to prove uncannily rare...? I worked myself into a mind-state where I Needed to Know The Answer before I could write the story; took me that long to decide, "oh, soddit, they're on a sodding plateau" and move on.

That was a few years back, and in another country. Living where I do now, I can go to SETI lectures about planetary geology; I can meet people who could answer that question; I can sit through lectures with it still trembling on my tongue before I remember that I still don't need to know.