Schedule+ had the concept of exceptions to a recurring appointment (RA) - meetings that didn't follow the recurring pattern (e.g. every week on thursday at 4pm).

This was exposed through the UI by letting the user adjust the date & time for the RA instance (e.g. move this week's thursday 4pm meeting to 2pm) via drag-drop or editing the RM instance and change the time in the appt dialog.

So I assume with Outlook you could schedule a recurring appt for the common case - weekly appt on wednesday at 1PM. Adjust as your needs require - no meeting needed? Delete this week's instance. Need to move the meeting earlier or later? Go and reschedule this week's instance.

Obviously wouldn't work if you needed two meetings in a week.