When I started our business in Pinellas County ,FL,1976,they soon mandated
duct layouts for each home ,that they did nothing with except file them.
So we did a few ,all with layouts showing every duct as a 4" round.Then after they were finished and passed inspection,I showed the layouts to the chief mechanial inspector,in protest as it was a waste of my time and money,to make and deliver them a copy to file away.
Big mistake for the next few months!!