That much work would give me a headache Steve LOL. I always keep a backup when I'm going to make major changes to any form, but I only backup the .fb file to a backups location and that's really all that's needed. Saving the exported stuff is kind of moot other than to keep the current exported folder.
Rick it's a very good idea to just copy and paste those files as some day the scenario will be that you have more than one menu on your page and you forget to rename the 2nd one to something else and it's now called the same as the first menu and you now just overwrote your first menu and didn't realize it until "after" you uploaded it and overwrote it on the server too, etc. etc.
I created a Form Builder Files folder that doesn't get uploaded ever. In there I keep my .fb files as well as any backups I keep of the .fb files. I export the menu to that location and copy the files from there to the root where they will be going. This is just a good practice so that you don't accidentally overwrite something that you may have not kept a backup of or lost the file for etc.
Just my 2 cents on the subject, but don't make it more work than is needed