I have 3 PCs, all homebuilt by me, and a cheap Chinese tablet.
One PC is still windows 7, all the rest are Win10.
All install Win 10 updates between 20 mins to 40 mins, with no fuss.
All my copies of Win 10 are OEM and cost between £2 and £10, for just the keycode number, Win 10 itself is always direct download from Microsoft site so guaranteed latest fixed version.
I would never buy a PC from a shop or dealer and never have any issues with my PCs that cannot be dealt with quickly and cheaply.
Most people who have come to me with update problems have PCs full of junk, seemingly never maintained and just run until they fail, from the cheapest to the most expensive.