> Sure she was “busy”, another patient took longer than she expected, blah blah.
Imagine if you had to do 10 short coding challenges, one after another, without knowing the full scope beforehand and had to say exactly when each one would finish. Now on project 9, your client shouts at you for delivering late because they are your CUSTOMER and you must not take them for granted!
Did she have to stop in the middle of someone else's appointment to deal with you?
Any story that goes "it happened for years without me saying anything then I got angry" would probably have been handled better for everyone if they'd talked about it to start with. Can't wait? Tell them!
Many people might have a spare half an hour and overall everything goes faster if occasionally the last person needs to wait 30 minutes so that typically more people get seen during the day. But no, because you have a requirement you've not specified, everyone else needs to deal with the consequences.
Or tell them when you make the appointment that you will have to be out by a certain time, there's likely to be a better place to be in the schedule.