Wow that guide is obsessed with the trading post . Trading post is only helpful when you have excess Garrison Resources (hint, shouldn't be for a LONG TIME) and none of the materials you can obtain from it are unique (like inn/barn functionality). Lots of these decisions come down to judgement.
I appreciate the idea but I really just wanted to keep it in house. I don't think I'd be to respond to the questions/criticisms from a potentially larger audience.