When it comes to a calendar/appointment scheduler, how important is the ability to schedule recurring events to you?

Yup, imo one of the most important features.

Very important. However for planning todos, shipping etc I need to put it in my calendar/planner and be a very conscious while doing it. Otherwise I don't read it any more. An automated weekly "finance admin" task in my calendar does NOT work... But a weekly go-to-gym event does work.