Moving the libraries is something that has been an option in Windows for a very long time. It allows you to use the same files across the different versions of Windows and is really handy in multi-boot environments. The reason I chose to do it initially was to keep the boot drive size small. The way you do this is to open File Explorer and right click on one of the Libraries (Desktop, Documents, Downloads, Music, Pictures, Videos) and choose Properties. There will be tabs on the Properties window and one of them will be Location. You can move the entire library and its contents by using the Move option.
I began doing this because originally my Documents folder exceeded the size of my first SSD even though that SSD was 1TB in size (even now that's a big SSD). My Pictures folder was another offender, and so was Downloads, and even Videos.
There is something you MUST be aware of when you do this. When Microsoft developed Windows 8 (or maybe it was 8.1) the OS would refuse to install if the /Users folder had been moved off of the C:\ drive. People had been doing this to keep the boot drive as small as possible, since they wanted to conserve precious SSD space. Several programs like Adobe Premiere, Photoshop, Audition, and probably many others that I do not use will maintain their media cache files in the User folder. DO NOT move the /User folder. Instead, move the cache. For one thing, the /User folder does not have the ability to be relocated. Worse, if you do that then Windows 8, 8.1, and 10, 10A will enter an unstable state and update issues will result. However, that is not always the cause of the frozen update issue.
The update I'm talking about is every update to Windows 10, since Windows 10 was initially installed. People that have this issue have run Windows update from the very beginning, but the update executes and does not warn them that the update did not work. Instead, the update exits smoothly as if nothing was wrong. The same is true of the W10A update. In every case the notification Window reports "Updates were installed," but the version number reported by the WINVER command remains the same.
Just so you know a little more; my system does not have an M.2 SSD and I have not had the update issue. I did notice that Windows had moved the base Library folders back to the SSD when I updated to W10A, but they were empty. It was just a simple matter of moving the folders again and everything I have in those Libraries is restored. In other words, I was not personally hit with the frozen update issue on my primary PC. However, I did have people that I know come to me with the problem and that is how I found a way to fix their systems so that the OS could update. When I found systems that still would not update I performed the return to HDD and update boot as my own fix and informed MS (yeah, I did that). I still have a few contacts that have not been able to run the update even with the HDD fix.