It also partly depends on how often you switch jobs that require you to learn a new programming language. So far in my career I've had to learn new languages q

It also partly depends on how often you switch jobs that require you to learn a new programming language. So far in my career I've had to learn new languages quite often, esp. on hacked-together projects with 3+ languages. It's not just learning the syntax but also the common idioms. Still, I'm pretty sure at least more than 50% of the time was using the language and not learning it, so the original statement stands.