Where I live an appointment is hard to get. I usually wait at least two hours to get a visit of 15 minutes. All doctors offices are like that here in Northern New Jersey.
15 to 30 minutes but I never leave before I have all my questions answered. The wait time is usually short as I arrive early and usually get in early. In the past, I have told the receptionist to cancel my appointment and walked out for an excessive wait, unless it is a busy specialist and they really had a good reason for the wait. If it was poor scheduling I let the doctor know and well as everyone else. The worst offenders are urgent care clinics and the ER. I avoid those places the best I can.