Most organizations don't have the need for 24/7 capacity since they don't need to use CI runners all of the time. The most work is done during work hours in a regular work week, and at the weekends, there's less of a need for software to be built. In this situation, it makes no sense to have machines sitting idle, waiting for jobs. By specifying a schedule with the OffPeakPeriods option, you can specify these times of lower productivity. During those times, the parameters to control the creation of the runner's capacity are different. You specify them by putting OffPeak in front of it. Therefore, IdleCount becomes OffpeakIdleCount, IdleTime becomes OffPeakIdletime, and so on. The functionality of the algorithm stays the same.

In the following schedule (which is common), you can see off-peak times on weekdays during the night, evening, and the entire weekend:

[runners.machine]
   OffPeakPeriods = [
     "* * 0-9,18-23 * * mon-fri *",
     "* * * * * sat,sun *"
   ]