For any setting that requires you to enter/select a date, it would be nice to be able to scroll through the calendar. This would align with most calendar based interfaces. If trying to schedule an override a month out, this would allow for a quick means to adjust the schedule.
This behavior is available on my on call shifts. You can highlight the days that you want to make an override and then select the schedules and escalation policy levels that you want to make overrides for.