Prior to 10.4, Mac OS X used cron, then scheduling became part of the job of launchd. Later Apple added a new subsystem, Duet Activity Scheduler, which continues to evolve.
CoreDuet
By default, your Mac’s cooling fans run at full blast. Only the control system slows them down when it is safe to do so. How to diagnose and fix its problems.
If Apple manages the performance of iOS, does it do the same with macOS? What is there to stop that from being used against us?
The Eclectic Light Company 