[NetMageSCW]

Actually once the initial backup is done there is no reason to scan for changes. They can just use a Windows service that tells them when any file is modified or created and add that file to their backup list.

[DarkUranium]

To an extent. WinAPI's file watching has a race condition in it, and there's no simple workaround (just complex & error-prone ones).

Well, for backups the workaround is a bit easier (as they strictly only ever read files), but still.