I'm going to go with banning tobacco.
The answer that the single most important thing is to regularly have a patient spend an hour or more (not a minute less) with a person who is highly trained talking to that patient. Obviously there's a purpose here where crafted conversation and observation are a means to an end. What does the patient think he has? What treatments are being given and what do they know about them? Are your other conditions why you are here? I went to a seminar on pain and the specialist was part of a team working with the VA to treat chronic pain and he is a psychologist who specializes in pain management. Often a significant other comes with the patient to be treated and on more than one occassion the pain could not be managed because of a domestic situation. No one gets better who is in active litigation in this guys 20 years on the job. Once it's over? Then progress can be made. Same with a nasty divorce and the like and I think to you at least this comes as no surprise.
So "how's the family/wife/job etc going" is not a pointless type of thing to ascertain, far from it. Oh, then there's that particular rash that's not part of the complaint, or maybe there's some physical sign like edema, but hey the guy has a sinus infection and so all of this is a time sink not related to the chief complaint so that melanoma or strange growth, or blood in the urine or the history of hepatitis not given before because hey it wasn't important to his sinus and he went to a different specialist, but there's signs of ascites. Oh, we're seeing signs of depression, and on and on, things that warrant a followup on a dozen or two observed things of that medical prudence dictates a practitioner look into now rather than waiting until there's a full blown case of FUBAR. This isn't a standard nurses job, not part of regular physician practice. That hour? That's likely not enough, with an hour and a half producing average greatest benefit.
To a practitioner as you are the benefits ought to be obvious because we are having a formal and well defined process of observation and patient participation for the purpose of preventative medicine that reduces long term costs and provides an upfront basis for assessment of
the health of the patient. But that's not what any existing form of insurance exists as a standard of care anywhere in the world, single payor or not.
Get them in and get them out. Assess the complaint, take up further action in that regard and treat with surgery or medication or occasionally mental health assessment. Get em in and get em out. Just think of the money it saves! and yes money is the metric of medical productivity and has been for at least 3 decades.
Care an inch wide without patient health, that is the person as (insert name here), not a disease state is what people are really asking for whether they realize it or not.
I'm not a fan. We need new paradigms and support structures and no one is talking about that, at least not so they can make themselves heard in "reform".