Settings - Operations - Business Hours.
Appointment time slot days being separated. Instead of having it clumped Monday-Friday, have each day separate. That way you are able to set specific hours for each day of the week when needed or show that you are closed. Example: Monday 8am-5pm, Tuesday 10am-5pm, Wed CLOSED, etc.
Also being able to over lap the time slot hours for booking purposes. Example Monday 10am-2pm, 1pm-5pm.
You should post this as an Idea in the Ideas tab on the top right of the home screen. Then come back and add a post with the ID so people can vote!
As far as the overlapping goes you can have overlapping arrival windows for scheduling/booking purposes.