I'd expect there's some corporate-speak maximum that happens in middle management, and upper and lower people would use it less, with the curve being flatter for more bureaucratic companies.
Corporate-speak is usually centered around covering your ass with ambiguity.
CEOs dont feel compelled to do that on "private" emails but they sure as hell do it in public statements. They dial it up to 11 during layoffs or being interviewed about unethical behavior.
As a first approximation, just think of the size of the destination audience:
- if it's a few people, the language will sound direct and casual
- if it's many thousands, millions (likely to include government, investors, customers) then it will sound formal, corporate, "PR"
Because we're more often likely to be in the 2nd category, we're used to hearing senior leaders sound like their words have been carefully edited.
But we shouldn't be surprised that when we get a glimpse of their comms in smaller settings, it sounds "just like us".