New
#21
Recent versions of Windows 10 should be fine with a non "FIXED" drive (though the official tool may not let you create it).
Up to another Windows 10 release that I can't recall right now (1803?), you couldn't boot Windows To Go from a non FIXED drive, but Microsoft finally realized that the days of non FIXED equating slow speeds were long gone.
Don't want to to look like I'm blowing my own trumpet here, but provided you use a retail ISO (and soon, with Rufus 3.5, this feature will finally be extended to MCT ISOs, thanks to stumbling upon a completely undocumented option that Microsoft appeared to want to keep to themselves), Rufus will happily create a Windows To Go drive for you.
Just select "Windows To Go" in the "Image Option" dropdown that should appear after you select the ISO. Oh and Rufus will also display a warning if you're trying to use an ISO that's incompatible with non FIXED drives for Windows To Go...
If you have a flash drive with >60 MB/s write speed, regardless of whether it's FIXED or not, you should be able to run Windows To Go on it with little trouble.
Oh, one thing that I'm just remembering and that might be important (it's in the Rufus FAQ), besides removing the "My Documents" folder, Microsoft also screwed Windows To Go in the 1809 release by using a buggy WppRecorder.sys driver, which will make Windows To Go BSOD if you don't replace that driver with the 1803 version. Unfortunately, that's not an issue they fixed with the October re-release of 1809, so it's still a very much active bug. So I would recommend using the 1803 release for Windows To Go, unless you know what you're doing. Btw, next version of Rufus will also warn you about this bug when creating Windows To Go drives (but we can't automatically fix it for the user, since we can't redistribute a 1803 WppRecorder.sys to replace the 1809 version, as that file is copyrighted by Microsoft).