Great Hall priorities when progress is slow (EU servers)

Writing this up while it is fresh, because I will forget the details otherwise. The in-game explanation and the actual behaviour do not appear to match.

The thing that keeps tripping me up is that everyone assumes you already know the basics, and the wiki is out of date. Still open to better approaches if anyone has one.

Short version: this changed for me after the last patch, so older threads may steer you wrong.