[csmdev]

Learn what? A new thing every year? How do they become experts then?

Just because you learn a new language or technology doesn't mean you become better at problem solving. It just means that you can solve problems using a different tool.

[facorreia]

They learn, for instance, about new developments in their field of expertise, and about more practices and tools they can leverage.

[themonk]

They become expert in problem solving.