I'd actually be curious to see an analysis of this. All of my experience suggests that there is indeed a significant difference in employee quality and a substantial cost imposed by turnover, but I'd love to see some data to the contrary, i.e. that the "employee as interchangeable cog" model is defensible.
I more meant there's no first-mover advantage, because a 'last-loser' can always adopt the better policies and poach new talent under the new regime.
There may be SOME lag, but being a first-mover on return to office will not make or break a company's future.