It is common to assume in the programming world that any competent programmer should be able to learn a new programming language in a few days and be productive within a week or so. Many will brag about their knowledge of multiple languages and how they did this in that and that in this.
I've found this myself. In fact, my last project required me to move between Bash, Java, Python and Clojure daily and sometimes throughout the day.
I wonder though if some sort of specialization might be better. In my last project I wished to focus exclusively on Clojure but that didn't work out.
Here is something to consider. Look at a symphony. Each musician is a specialist on one instrument. Sure, many if not all will know how to play the piano. Some will double on other instruments. Many will know how to play each somewhat but each ultimately is a specialist on a single instrument.
Would this work in the programming world? It would be nice especially if you are a specialist.