Schedules are used to determine when policy rules are applied. You can add one or more schedules to a rule. It is also possible to add a schedule as an exception. For example, you could add a schedule of midnight to midnight to a rule to always block a specific website. You could then add a schedule that runs from 12:00 to 14:00 as an exception to permit users to access the website during their lunch break.
Schedules are applied in order of length (time duration), from shortest to longest. So in the previous example the schedule to enable user access from 12.00 to 14.00 would be applied first.