If you know three programming languages within a paradigm, you can pick up another in a couple of weeks. You can write something simple after a day, but learning the API takes a bit more time.
If you know programming languages within three different paradigms, you can learn a language in another paradigm as quickly.
If you only do high-level stuff, moving to a lower level closer to hardware is harder than the other way round.
Moving to another paradigm within one programming language, say from MVC to a continuation-passing web framework or from a game library like SDL to an entity-component framework or from PostgreSQL to Redis, or from gradient descent to bayesian filtering, can also take some time.
If you know a couple of concepts and paradigms, you start working on day one, but you will only be really productive after a coupe of weeks.
That said: If you have trouble understanding a concept like distributed version control or object-oriented programming or shader pipelines, it is orders of magnitude easier to ask an expert to help, tell the expert what you think you understand, and let the expert tell you where your understanding needs to be updated. Experts can tell you where you’re wrong. If you learn a new paradigm, you can get stuck on a fundamental misunderstanding for some time.
Specific instruction from experts is great for that reason, even if you can pick stuff up on your own.