My guess would be that you don't always use the middle of the interval, but choose knowledge of the history to guide your choice of the tested revisions. e. g.

My guess would be that you don't always use the middle of the interval, but choose knowledge of the history to guide your choice of the tested revisions. e. g. recently I was debugging a problem, after two halvings, I saw there's a big refactoring in the remaining interval, so I picked the revision before/after.