It is irresponsible to show up to an appointment late.
Tanya has 20 minutes left in her favorite show but has to be at the dentist in 10 minutes.
Tanya wants to finish the episode she is on.
Tanya sets her DVR to record the rest of the episode, so she can watch the rest after her appointment.
Tanya finishes the episode before heading to the dentist's office.
The dentist is able to keep to their schedule and Tanya is able to finish her show.
Tanya is late and throws off the dentist's schedule for the rest of the day.