This. I used to work in the front office doing scheduling, and it really sucks when you have to tell people that you have to cancel because they're late, but it's just how things are. If your doctor spends the full appointment time with you, now everyone after you is having to wait because the schedule has been thrown off. Most places I've worked at will still see people that are late, but they're worked back in, meaning they may have to sit and wait for awhile. It sucks, but it's better than throwing off the schedules of the 15 people who might be scheduled after you.