When choosing an ongoing frequency for Maintenance [PM], options appear as follows:
The first option is selected by default.
This option simply provides for subsequent Work Orders to recur regardless of whether the previous Work Order is completed
The second option is a bit more complicated and results in two additional options once you select it
This option provides for the scenario when the previous Work Order has not been completed by the Requested Completion Date (i.e. if Daily, then the following date)
Notice that the 2nd additional option (selected by default) provides for subsequent Work Orders to generate after each previous Work Order's Requested Completion Date (again, if Daily, then the following date after the Requested Completion Date)
The 1st additional option (when selected) provides for subsequent Work Orders to be generated (only after the previous Work Order is completed) according to the Frequency selected (i.e. every day, every week, every month, etc.)