According to [1], in 2015 Google averaged 25 commits per minute (250000/7/24/60). I can imagine hundreds per minute during Pacific working hours today.
In the case of a monorepo, that's exactly the case why the build system shouldn't be overly complex. If you're expecting random people to make changes to your stuff, you shouldn't be burdening them with more complexity than necessary.
The monorepo case is also a little bit outside what I was originally talking about. I was mostly refering to individual services/libraries/apps
[1] https://cacm.acm.org/magazines/2016/7/204032-why-google-stor...