Well, the measure of efficiency most of the world cares about is “overall profit”, which — around the efficient frontier — has a good proxy with “overall output”.

I feel your “output per worker” measure of average individual efficiency is not a good metric to optimize - just fire everyone except your best employee and you’ve maximized it.

Edit: employer -> employee typo

I think your first point is good and agree with it. Even within optimizing for that (rather than output/worker or output/salary), I think it's fair to examine whether specific choices are optimized for the same case that you are facing. Not everything done by very successful companies should be replicated in your business.