Where to Locate Desktop and Download Folders
When I set up a fresh machine, I move Documents off the system drive and put Downloads, Music, Pictures and Videos under it. They're all just folders in the user profile, so it makes the profile smaller and makes it easier to restore a system image if I need to without disrupting my data.
I don't move Desktop, as I only have a set of standard shortcuts on it, but YMMV.
Note this will also work on a single hard drive with 2 partitions.
Redirecting can be done through Registry scripting, although in Windows 10 sometimes I still need to fix things in the folder properties.