Yeah, I did a 4-way search like this on gcc back in the Cygnus days - way before git, and the build step involved "me setting up 4 checkouts to build at once and coming back in a few hours" so it was more about giving the human more to dig into at comparison time than actual computer time and usage. (It always amazes me that people have bright-line tests that make the fully automated version useful, but I've also seen "git bisect exists" used as encouragement to break up changes into more sensible components...)