The Mayo Clinic is one of the best hospitals on the planet and is even mentioned in the article, since they have diagnostic labs that specialize in so-called esoteric testing. Their doctors are paid a salary, which is market-based, reaches a plateau after a number of years you have the same title and is not tied to the number of patients you see. Not only there's no incentive for them to cram as many patients in a day as possible, but they call each other consultants because they will bring in colleagues when there's a tough case that warrants a second or third opinion.

In fairness, it's the Mayo Clinic's enormous prestige that acts as a supplemental non-cash reimbursement to the physicians that practice there. It's, more generally, a trait of hospital systems to substitute reimbursing physicians with culture rather than cash. They get a flat salary, and in some places a volume-based bonus. In places where the culture isn't earnest, insufficiently prestigious, or both, this cultural currency falls flat and physicians (and other staff) absolutely start to suck more.

Outside of hospitals (hospitals and physicians are not equivalent; think Walmart and your local mom-and-pop shop, if you want a better idea of the relationship between the two), physicians are reimbursed directly by volume. Not quality, though - just volume.