The idea of keeping your personal files separate from the hard drive that contains your operating system also means a crash of that OS drive does not also take out your personal files.
In Windows 10, you can now select where your new Windows apps from the Store will install and save data to by default instead of on the Windows drive.
Changing your default save location creates a new Users folder structure on internal or external drive, including SD cards, USB drives, and USB flash drives.
Another interesting thing you can do is set a removable drive as your default save location so whenever that drive is plugged in, Windows offers to store new files on the removable drive.
When it’s not plugged in, Windows saves to the original location.
If you like saving your personal docs on a flash drive or external hard drive so you can carry them with you, changing default save locations might be useful.