I've always taken the children back when it is a morning appointment, and they can arrive back before nap time, so I don't think I'm being unreasonable. Schedule appointments for after nap time and take them home early is my usual routine for parents. I guess the part that gets me is that they are done work, and at home, they don't have to race back to the office.
Of course it is one of those kids who is here usually from the second I open until the second I close, even though it's usually about 3 hrs less that they truly need. I guess they want some free time without kids. It drives me batty! Why come back for an hour?