That's when you can use "cut" instead of paste fairly safely and the files stay in the same place, just the file table is changed to indicate their assignment to a different folder. No actual copying is done.
Why I do this is unimportant. In Win 7, when I move my daily backup files (2 weeks worth about 20gb) from my current BU folder to my save BU folder, the move took a couple of seconds (I think because only the file pointers were changed.) Under Win 10, it takes in excess of 2 hours (I think there is a physical move of file data.) This is my third try since installing Win 10 on my (admittedly slow) server. Is there a way around this? Will renaming the files work?