Most of the work in finding/fixing bugs is reproducing them reliably enough to determine the root cause.
Once I find a bug, the fix is often negligible.
But I can get into a rabbithole, tracking down the root cause. I don’t know if I’ve ever spent more than a day, trying to pin down a bug, but I have walked away from rabbitholes, a couple of times. I hate doing that. Leaves an unscratchable itch.