I respect your position here and don't intend to be on the attack. Usually that one client also lacks other compensating controls, particularly around privilege managemetn and internet access, and the lack of patching is a convenient excuse. If "exploit Wednesday" is an issue for you, something is wrong.

In any non-trivial enterprise, Windows 10 has an operational model that's being rebuilt in flight. You need to exert a level of testing every six months that previous Windows versions required every 2 years, and you have to deal with the rubix cube of servicing editions of when a random feature that you care about is twiddled or taken away in Office or Windows.

Alot of the hard work and creative engineering that gives a near-legendary and seldom mentioned track record of backward compatibility in Windows is being squashed by poor release management. End of the day, we have computers to use as tools to do things, business comes first. The philosophy within Microsoft has changed in recent years, and now there seems to be an attitude that running Windows v.now is the primary mission of every Windows PC. That's truly an unfortunate thing in my eyes that makes me sad -- Windows is an amazing platform that could be so much better.