This seems correct to me. The last two things I've learned were javscript/node/react and Haskell. I had never touched js or html before, but within two days I had a pretty decent web app up and running. It was something that could (and did) provided value for a business.

Two days after starting Haskell I had essentially nothing to show for it except a feeling that I has a huge amount to learn before I could be productive. Even a year later I still have a huge amount to learn.