@Alan-Kilborn
Thank you for your insight.
I guess there are many ways of working.
I am in an environment where add-ons are not readily available. Using the native capability over time has been my best option, and so I have not explored alternatives.
Backup is not a deprecated feature, so expecting it to be reliable, as I do for any other saved file.
Whether the number of un-named files is large or small, this highlights what can happen when the user changes the saved location, and is, I now think, a good case for consideration when designing or testing code modifications around the backup location.