Somehow, I've managed to put a lot of what I know to some professional use, whether it's my ability to write, edit, speak, teach, take good photos, or, most unexpected of all, my love for gemstones.
I suppose honing skills that can be used in multiple domains is never a waste, even if you don't consciously think that you are developing those skills.
And perhaps that's the secret - to unconsciously improve them, not necessarily as part of your professional life.