The dogma of modern medicine is that it should be evidence based. Well this is true but in actual day-to-day practice the evidence is often only marginally helpful.
In actual fact we practice a lot of medicine based on gut instinct. And this gut instinct is learned from doing the same thing over and over again, by seeing similar cases and recognising what the outcomes will be. This is a type of evidence based medicine which we might call experience based medicine.
Let’s tale the example of dose-adjusting chemotherapy. There are guidelines about what to do but when you take a phone call you invariably don’t look up a guideline. I adjust the doses partially based on guidelines and mostly based on my experience of what will happen with dose adjustments. The reality is that practice makes, if not perfect, at least better.