Automatic backup does "full" backup

[JoeKoko]

Why, as in under what circumstances, would automatic backup do a full backup
instead of an "incremental" backup (just new and modified files)?

I started with a full backup on 6/8 and turned automatic backups on. The
schedule was once a week. I was puzzled as to why I was getting less than two
automatic backups on a DVD-R. When I investigated, the incremental backup
showed files that haven't been touched in months, let alone modified, were
being backed up.

Anyone have an idea what's going on here?

 

[Mark L. Ferguson]

If the full backup is more than one month old, a new full backup is made.

 

[JoeKoko]

As I said in the post, I do weekly automatic backups, the last full one being
two weeks ago. I appears that each subsequent so-called incremental back up
was indeed another full backup!

Koko