I learned this the hard way, I forgot to commit for a single day and got burned really bad when my regression tests failed and I could not trace the issue(it is called source control for a reason). I declared it was more efficient to revert back to the last commit than spend time fixing broken code that I had no fucking clue where it was and the only thing I had to go by was that it happened between two commits with a whole work day between.
A lot of you have a lot of faith in people reviewing PRs. I know a few Sr. developers, that if shit was too busy, would skim it and say 'fuck it, it will be QAs problem. If you put this in the correct sub-system in file that would only be executed once a month, for example a maintenance class, It would be really hard to notice something is wrong if it didn’t cause issues seen immediately. Maybe this is the story of an intern that added something that also fucked up boolean comparisons in a subsystem used once a month. Where there is a 2 week lag between the execution and operations noticing something wrong.