Never thought I would read so much rebuttle from people for a simple request, just because they don't use the feature.
My children each have their own callender's and on my Mac, I copy and paste existing calender events with ease. It is so much easier to duplicate a calender event with all of the matching text and notes, and then just modify the date. Creating a new event on the correct date and then trying to go to the original event and do 4 or 5 element copy and paste is backwards.
CASE 1: My kids are on similar teams, or in the case with tennis, the same team. DUPLICATE, change calender, done! Same with practices. Then, when one of them has a schedule change, just their calendar gets modified as appropriate.
CASE 2: The repeat is not intelligent enough in some reoccurring features. Such as when I set up a practice which repeats Mon, Tues weekly, with details including location, time to travel etc. But repeats on Friday at a different hour. Much easier to DUPLICATE, with all detail, then just change time.