Confidence intervals don’t have precise timelines associated with them. Sometimes you know exactly what the problem is when you hear the symptoms.

We always balance new work versus cleanup. I always have a laundry list of beefs with my own work. You often have a sneaking suspicion that this piece of code is wrong in a manner you can’t quite put your finger on. Or you do but a new customer is trumping a hypothetical error. Or ten people are blocked waiting for you to merge some other feature. And then someone gives you a test case and you know exactly what is wrong with it. Sometimes that’s fixing a null check, an off by one error, or sorting results. And sometimes the repro case basically writes itself.