I saw a video recently from a ... less sophisticated place in the US... where the HVAC installer literally held up a piece of paper from the street with different sized houses on it, and sized the HVAC based on which of the houses best "covered up" the actual house when looking through the semi-transparent paper. Just astonishing. No consideration at all for the build quality/insulation details, no adjusting for the distance from the road, just a "welp, this looks like a 3-ton job".