First, the problem isn't easily fixed. Here's the deal: At her HMO each doctor has a panel of several thousand patients. Each patient visit during a normal clinical day gets a 15 minute allocation with the MD. It used to be 20 minutes at her HMO but was recently reduced in order to increase the patient volume. Typically my wife's schedule is stacked appointment to appointment from 8-Noon and then again from 1-5pm. A couple of time slots are left unscheduled for high priority, emergent visits (if you've got a routine visit, forget it, you'll get something a month or two out into the future).
No as you can imagine, 15 minutes per patient isn't much time. Some patients require more time. With each successive visit, the wait will get longer and longer. This isn't because the doctor (at least some of them) is being a jerk or dismissive, it's because they're trying to do a thorough job with the time allocated. If they can't finish what they need to in 15 minutes, well, she goes over that time. It isn't too hard to realize how screwed up the schedule can get after a couple of tough back-to-back cases.
My wife then tries to catch up during lunch hour because she doesn't take lunch. After working through lunch, she kicks into the afternoon half of clinic hopefully caught up, but sometimes not. And the cycle repeats itself.
The receptionists can't "easily structure" the appointments more appropriately -- at least at the large providers -- b/c they're not the ones running the game.
I'm not going to defend the overall system. That's a much bigger problem and mess that a lot of smart people have looked at and have yet to solve. But I do think it's worth realizing that, yes, many doctors do think your time is valuable and don't purposefully try to waste your time. Many doctors are overworked and are doing the best they can within the parameters of what they've been given to practice medicine and that at some point you might be that person that has an appointment that goes over the time allocated (and when you do, hopefully you'll be happy the doctor ended up being attentive to those needs).
Just hoping to lend some extra perspective (especially as someone who used to feel the same way you do).
The healthcare world is directly analogous to the auto repair world, we just don't fit in the same place:
You, car, mechanic :: Insurance co, you, doctor.
The problem is that meeting a doctor cannot be planned perfectly. A meeting might take 5 minutes, or it might take 20.
If, on average, a doctor can serve 4 patients an hour, and she wants to reach that on a 9-5 working day, she must schedule her first patient at 08:45 or thereabouts. Reason: the first patient might be late. That would give her idle minutes that she would need to serve later patients, some of which might take 20 minutes.
Similarly, she must schedule her second patient at 09:00-ish, to have a patient waiting in case the first one happens to take only 5 minutes to serve.
And yes, that appears rude, but mostly, it is the economical thing to do. You can only get better service by paying your doctor more. You will notice that many people who can afford that are willing to do so. As an extreme example, I doubt that the president of the USA has spent much time waiting for his doctor.
For the maths behind this, google queueing theory.
As for structuring appointments more appropriately, it's quite easy to think of reasons an appointment could take more time than anticipated, and if you had to buffer for that time, you would have to pay for the buffer.