Desirable difficulties like testing and spacing make knowledge stick. It becomes durable. Desirable difficulties like making connections and interlea… - David Epstein

The most momentous personality changes occur between age eighteen and one’s late twenties, so specializing early is a task of predicting match quality for a person who does not yet exist. It could work, but it makes for worse odds. Plus, while personality change slows, it does not stop at any age. Sometimes it can actually happen instantly.

Interventional cardiologists have gotten so used to treating chest pain with stents — metal tubes that pry open blood vessels — that they do so reflexively even in cases where voluminous research has proven that they are inappropriate or dangerous. A recent study found that cardiac patients were actually less likely to die if they were admitted during a national cardiology meeting, when thousands of cardiologists were away; the researchers suggested it could be because common treatments of dubious effect were less likely to be performed.

Overspecialization can lead to collective tragedy even when every individual separately takes the most reasonable course of action.