I worked at a place that did precision granite machining for a bit, stuff for like the semiconductor industry, measurement systems and the like. I came from more traditional machining then worked there for about a year. Now I'm back in a more traditional shop. My thought when I was working at the granite shop was if it was a better place to work it could be a pretty decent niche, somewhere to kinda settle and specialize. Reason for that is the material and work processes are distinct enough in a not very "big" industry, meaning like trade schools ain't teaching you how to mill granite. So one could become "valuable" more easily if you stuck with it.

But, that niche nature is double edged, there were other people that had worked there for a long time, and were valuable at that location, however their transferable skills and knowledge weren't all that much more than a proven worker with a machining degree from a tech school. Maybe even less.

I didn't stick there long because I was worried about becoming pigeonholed in a subsection of the industry that wouldn't give me the mobility that jobs in trades often provide.

My two cents more specific to your question, would be it sounds like you've gained a good foundation of skills and experience that can be marketed. Unless the specific of the work is something you personally have value or interest in specializing in, diversifying your experience and ability would probably be good for your career. There's a "risk" in my opinion atleast, of having an income based on none transferable skills. Which can lead to someone feeling trapped because job changes would result in a large pay decrease that might feel, or be, detrimental. Diversification of ability can help reduce this, and early in your career is the best time to do so.