The guides apply to unmodded campaigns, or lightly modded campaigns (things like removing forts, faction unlocks, additional units, graphics mods etc.).
It's mostly based on campaigns I played before, but for factions I played less I did a lot of testing. So I decided to did some research and write my own guides. All advice was awful, or only applicable to outdated patches. As I got back to Empire Total War, somehow I couldn't find any good faction guides.