Exactly. And even if I do know the source pretty well, that doesn't mean I'm caught up on all the new changes coming in. It's often a lot faster to bisect than to read the log over the month or two since I touched something.

Even so, normally anything like a crash or fatal error is going to give you a log message somewhere with a stack dump that will indicate generally where the error happened if not the exact line of code.

For more subtle bugs, where there's no hard error but something isn't doing the right thing, yes bisect might be more helpful especially if there is a known old version where the thing works, and somewhere between that and the current version it was broken.

Or they were barking up a wrong tree and didn’t know it yet, and the rest of us were doing parallel discovery.

Tick tock. You need competence in depth when you have SLIs.