How does CPM work in the “Fixed CPM” strategy?

With the “Fixed CPM” strategy, CPM is determined by the current impression cost.

If the CPM value changes in the course of a line, then the new value will take effect no later than two hours after changes are saved.

If the CPM changes several times within one hour (between N:00 and N:59, where N is the hour), then the last change that was made will be the one that takes effect.