[NikolaNovak]

In big enterprises, core production infrastructure frequently has NO access to internet, ever.

Most places I've ever worked in will have local repositories, procedures and timelines for anything from Microsoft and OS updates, to development stacks and libraries.

Neither workstations nor servers get updated directly from external/vendor/open repositories - it is all managed in-house.

Slower, yes; more work, yes; but that's exactly the type of issue it's meant to prevent :)