Appointment Prep and Finish Times allow you to make exceptions for how available your staff, services & venues are.
For example, lets say you have board settings that don't allow overlapping appointments by venue or staff member for all your services.
But, you want to make an exception for a certain service that has a lot of down time in the middle -- like Acupuncture. This downtime can be used to start a new appointment or wrap up another that's occurring simultaneously.
This exception on a service level can allow you to stagger appointments just for this service.
To get started with making a Timing exception, click Appointments > Services > edit the service in question and scroll to Timing > select changes and save at the bottom.
Note: in order to toggle on the 'specify' option, above it you'll first need to select 'add buffer time' or 'do nothing'. Until then, the specify toggle will be greyed out and un-clickable.