We setup a recurring event – it starts and ends at the same time on most weekdays.
For one day when the hours will be shorter, we added a single event within the recurrence pattern.
See http://prntscr.com/eqe9lb for screenshot of our series pattern.
On the front-end, however, it shows both the original pattern and the exception (2 events) on that date: http://prntscr.com/eqeawi
If we add an exclusion for that date, it shows neither event.