Since the upgrades are forced on everyone, unless you have a computer like one of mine that crashes when MS tries to push an upgrade (and then reverts), in theory, everyone is running on the same version.
Not true. Windows 10 Pro, Education and Enterprise versions can defer feature updates (i.e. the big semi-annual ones) for up to a year. This would need to be specifically configured in Group Policy though. Our organisation has thousands of Windows 10 boxes I imagine, and we're all still on 1803.
You cannot normally defer these updates in Windows 10 Home without fiddling in the registry. But hey, what business is using that version, right?