Thank you. Your response was intricately and adequately descriptive.
(But, Yes, I've lost months of work because my 'saved' projects were automatically deleted.)
Please don't take any of this as being unappreciative. You obviously know your s**t.
My complaint is the counterintuitive presentation and use of the words 'save' and 'temporary'.
The constraints in language of - 'Properly saved files to a user defined location are not treated as temporary' begs the question because the location is determinent and not the file type. All the file extensions are the same and thus, all the files in the targetted location will be deleted. They are not temporary files, they are made temporary by being placed in a location marked for deletion.
Meaning - 'Saved files to a properly defined location are not treated as temporary' would be more accurate. None of which is conveyed in the menu prompts.
(It sure would've been nice to know this before the recent carnage.)
Perhaps if the 'Auto delete temporary files every:' ,,, setting was put on the same Preferences - menu page as the 'Auto save project every:' ... setting and to be so bold, clarity can only be achieved by replacing the word TEMPORARY with ALL until the addition of a Browse/pull-down for 'Properly saved files' is added. At least then, the apparent potential for carnage would get a 'Hey, Wait a Minute...'
I appreciated your input.