Found out while searching for other stuff: Microsoft actually did the needed patching for W10 1909 in the September and October monthly updates, and the features were installed but not activated. That is why (if going from 1903) the update takes so little time - it is turning on the features already installed. (this information was from an official Microsoft page)
Speaking of IOS updates - i NEVER update the phone or tablets until the update has been out for close to a month, and I'm not seeing people in mass complaining about it (with the single exception that, when I got the new iPhone 8+, I did not unpair the iWatch 4. So - the system was trying to swallow ALL at once - IOS 12 to 13 AND watch OS 5 to 6.
It all did work without major problems, there were a lot of little things I had to do manually; but it stayed in update for quite a while.
I'm really liking the 8+ as compared to the standard size 6.