I do not overbook or play other scheduling games. I consider my patients' time to be as valuable as my own, and strive to stay on schedule (although this isn't always possible). However, an open appointment slot is lost revenue.
Consequently, I expect people to keep their appointments or cancel with at least 24 hours' notice to allow another patient to have their appointment slot.
Our cancellation policy is posted in the lobby, and is part of the financial agreement that patients sign when they become patients of our practice. Patients also receive an automated phone call two days prior to a previously-scheduled appointment reminding them of their appointment and allowing them to cancel if needed.
The first no-show is usually excused, although we do make a point of re-explaining our policy to those folks.
We typically charge a no-show fee after that. The fee is $25, roughly the cost of a co-payment. It's intended as a deterrent, not to replace the lost revenue from the missed appointment. Patients who repeatedly fail to keep appointments may be dismissed from the practice.
Patients who arrive more than 15 minutes late for their appointments are typically asked to re-schedule. This is generally left to the discretion of the doctor, however...if we have time to see them without getting behind, we usually will. Likewise, if the appointment is for something that can't wait, we'll try to be accommodating. Again, a missed (or rescheduled) appointment is lost revenue.
In either case, we don't penalize people for genuinely unavoidable circumstances.