She doesn't do statistical studies, no. But I think she has good sense of the relative confidence she can have in "new discoveries" and older institutional knowledge (which also isn't 100%). And sometimes she puts in more time and attention than a few previous doctors did, considering all the symptoms and previous attempted treatments, to come up with an accurate diagnosis and effective treatment. By not being dogmatic, and spending a bit more time, she can fix some things.

I don't usually "do science" the statistical way either, I usually come up with a plausible theory for a bug, fix it, and use the results to confirm or refute my theory of that one bug. Usually it's something dumb, simple, and obvious in hindsight, not a whole new algorithm or technique.