Agreed on all parts. The Erlang and OTP manuals were very nicely written, and I was able to reason about most aspects of the system pretty well from reading them.

I did a bit more research after writing up my comment (my mind got a bit too focused on it to let it go) and found this great resource about handling various system load scenarios: https://ferd.ca/handling-overload.html

I'll +1 your pragmatic comment on not adopting tools just because they're there.

Again I no longer work in Erlang, but I find the systems, architecture, and problem solving particularly interest piquing.

Now I'm off to look up production use-cases where Mnesia was the most pragmatic solution.