Incorporate an option to describe an event as recurring and select the frequency of recurrence.
Considerations for flexibility of this feature, from a conversation on Space (https://discuss-space.wmflabs.org/t/can-the-software-remember-locations-for-recurring-events/2543/2):
"In recurrent events, part of the infos will be, by definition, constant, but, and that the point, not solely the date will be variant ; some other “fields” may also vary, systematically or from time to time. For instance, the theme of each peculiar session, the type of awaited or targeted public, the precise location (rooms prone to change)"
Feature must allow for changes to these fields on particular dates.