Does anyone publish separate topic-specific "series" within a single newsletter?

I'm writing a few Substack newsletters on different topics. I'm curious if there is precedent for combining different topics into one newsletter name-spaced by series.

For example, I've started one newsletter that covers critical infrastructure (risk, policy, data, systems theory, social divides, policy, etc.) and one that offers succinct analyses of topical issues like E2E encryption. The alternative example would be a Critical Infrastructure series and a Digital Security series in one newsletter, united by similar editorial tone/formatting/author.

Knowing myself, I could easily create a handful of other newsletters in the coming weeks—on jiujitsu, physics, medical science, philosophy, etc. And that might be a great way to test a bunch of ideas in isolation and stick with the ones that work. Or it might be a great way to create a single, omnibus newsletter with separate series—forming a dynamic whole.

Thank you for any thoughts or examples!