Maybe he meant, for example, that a 1st year cardiologist is probably going to be a better cardiologist than a 20 year nephrologist. The OP seems to be insinuat

Maybe he meant, for example, that a 1st year cardiologist is probably going to be a better cardiologist than a 20 year nephrologist. The OP seems to be insinuating in his medical analogy that only time - not specialty - is the most important metric. Take that 20 year nephrologist: if he had spent 10 of those years in cardiology, I don't think most other nephrologists would say that makes him a better doctor just because his experience was more balanced across two fields. In fact, I think they'd say he was a lesser doctor than one who devoted the 20 years to one subspecialty.