You can now add a grace period for cancellations. If a student books an appointment, and needs to cancel ~5 minutes later, you may not want that to count towards any maximum cancelled appointment rules. If a student cancels within the number of minutes specified here, the appointment will be deleted instead of set to a cancelled status.
This option can be found in Other > Profiles > [Your Profile] > Prefs > Scheduling > Time Restrictions > Allow cancellation/deletion of new appointment within x minutes.