Of course I still learn new skills in the Python/db ecosystem, but I stick to the fundamental Python/Postgres/Flask/Django/Redis/Nginx stack where possible and it not only helps productivity but it reduces surprises. We understand the exact risk profiles of these systems. You can "learn" a new tool very quickly but you won't know how to assess or reason about what will be the operational experience of it in production. We do not factor surprise tolerance into our decisions often enough.