Where do you find 2006? My googling says NT 6 was released in early 2007, so I meant that on Jan 1 2007, Win 5 was still current. https://simple.wikipedia.org/wiki/Windows_NT_6.x

It wouldn’t make a huge difference to me if 6 was released either 6 months earlier or 6 months later. In 2007, NT4 was only 1 major version behind for most people; adoption takes time. The broad timing of major versions being 4-5 years apart didn’t change until Windows 11, and we don’t know if that’s an outlier yet, but we do know that Microsoft has been changing the Windows release strategy, with more frequent updates. https://endoflife.date/windows