Yes and no, I think decreasing returns is a real thing. 10 years a long time, and you can explore whatever cave you started out in in that time. People regularl

Yes and no, I think decreasing returns is a real thing. 10 years a long time, and you can explore whatever cave you started out in in that time. People regularly go from high school to PhD in an obscure specialty in 10 years. However 10 years is also enough time to explore the depth of one cave along with the openings of 5 other caves. That T-shaped skill set really gets wider in the next 10 years, at least it did for me. The width is also what tells you what you haven't looked at. For me it's Haskell and LISP. Not sure if I've got the monads to go down that route, it might overturn my existing long learned wisdom, something that could be painful with 20 years of experience.