If you have an event that last over several days or months there is the option to create an event series instead of entering each event as a separate event.
When creating the event, enter the time for the event on the first day, then select the “This event repeats” checkbox. After selecting, you’ll be given the option to select the frequency of the event, choose the dates for the events or the number of occurrences.
By using the series function and a change is required for the events, you can edit the one series event, instead of each individual event.