I found this Python script a few years ago, it is simple enough that a non-programmer could understand 90% of it. I just remembered it had been running as a scheduled task all this time when I thought I had lost some saves.

Thought I'd post it here in case anyone can use it. Minor things are hard coded but they are few and easy to edit.

https://github.com/nonbhoward/backup_factorio_saves/blob/main/run.py