A year is enough time so your new language stops teaching you new things every week. I agree that superficial knowledge can be attained quickly, but learning th

A year is enough time so your new language stops teaching you new things every week. I agree that superficial knowledge can be attained quickly, but learning the idioms, tooling, libraries, gotchas, performance bottlenecks, warts, etc. takes months. Maybe six months if you're very good, but I'd wait a year before assigning a big project to someone new in a language/framework. Still wouldn't consider them a master with just one year of experience, mastery of a modern language can take years, you can always go deeper.