One good idea w.r.t balancing acquisition and polishing of existing skills is to shape your knowledge to the letter 'T'. The long-end of 'T' represents the stuff you think you're good at (and optionally but helpfully, you like) or have already invested most of your time on so you keep specializing on its sub-branches. And like the two short ends of 'T', you invest time to acquire new skills which in this case might be new frameworks, languages or a different domain altogether. You don't need to be an expert here—just need to know enough to be dangerous. Rinse and repeat—as you grow, you can go beyond two short ends and one long end. You'll grow to be formidable and hard to disregard in any team you present yourself in.
One good idea w.r.t balancing acquisition and polishing of existing skills is to shape your knowledge to the letter 'T'. The long-end of 'T' represents the stuff you think you're good at (and optionally but helpfully, you like) or have already invested most of your time on so you keep specializing on its sub-branches. And like the two short ends of 'T', you invest time to acquire new skills which in this case might be new frameworks, languages or a different domain altogether. You don't need to be an expert here—just need to know enough to be dangerous. Rinse and repeat—as you grow, you can go beyond two short ends and one long end. You'll grow to be formidable and hard to disregard in any team you present yourself in.
I will do you one better, go for W shaped curve. Be quite good in 2-3 things and competent in rest. For me, thats where the "big-W" is.