“An expert is a person who has made all the mistakes that can be made in a very narrow field.”
Niels Bohr
Which is why aspiring medical doctors and structural engineers are closely supervised for a few years after graduating. Mistakes they make can cost lives.
But, hifi engineering or setup experts are expected to perform on day one—And make mistakes. Though companies generally place newbies in less demanding roles, their skills are put to the test on lesser products or "typical" systems on day one. And, why not? They know more than most of the customers they will eventually serve.
Or do they? After all my years of playing expert, I am constantly humbled by more experienced customers.
We've been conditioned to turn off our critical skills in the presence of an expert. But, increasingly, that notion is being supplanted as we uncloak experts from mythical status to simply people that sometimes have more experience and knowledge gained through many mistakes as we do.
Experts are great as long as they are nearing the end of their mistakes within a narrow field.