"Deleting unwanted files" How and which files based on date?

The backup process explained might go along well with the above (which I prefer, but it’s more technical).

suggests you’re at least somewhat technical, and the answer to that is no. It uses timestamps then reads contents of candidate files to try to figure out which blocks changed. The job log counts what was opened.

Cost optimisation on wasabi gets into that issue further. If you’re an expert on their charging, you can post.