OP here - I can touch on that. Didn't really expect anyone to read this post, so it was rather brief and just focused on how I've automated out the tedious parts of maintaining my server.

However, I still build new things, launch new services, etc. I personally don't categorize that as maintenance.

In regards to your complexity comment - I have slowly built up experience over the years and now launch services where I very rarely have to edit compose files or such. However, it does happen and I would lump it into that "~15 minutes per month" bucket. I primarily use Nginx + Docker for any service I launch and can quickly diagnose issues and resolve them.

Perhaps another piece I could've mentioned is sticking to a core set of tools like this, which allow me not only to automate the basics, but also to have become adept at fixing things manually if they break.