> If you can't be an expert after 5 years then there is no such thing as experts.

I think you’ll find that after 10 years one’ll look back on oneself at 5 years’ experience and realise that one wasn’t an expert back then. The same is probably true of 20 years looking back on 10.

Given a median career of about 40 years, I think it’s fair to estimate that true expertise takes at least 10–15 years.