Saving Money with Builder Governors

If you have a governor accumulate retinues/traits that reduce building costs: have him line up several buildings in a city you are about to build up and move him to build up the next one. The building costs (a discounted version) are charged at the time when you order the construction with the builder general in the town regardless of who is in charge when you actually build them (even if its auto-manage)... saves $$$.

forgot to mention: this is about RTW! :)