I have certain files and directories which accumulate more data over time. I had been storing these within the blog itself in a /cumulative directory, but that was making backups of the blog itself quite large. So I've repositoried them on my GDrive, pCloud, and box.com, as well as on my OneDrive. Just look for a folder on those cloud repos entitled cumulatives.

This shrank my fp-content.zip backup from ~52 Mb to a bit over 2 Mb.