2 stage air for shop tools is quite an improvement, the exact math really isn't important as is that the working range is in a set of pressures another level higher making for consistent regulation. Working range as said earlier of 135-175 vs 90-135 at best. It isn't to make more cheaper. There is some more stored energy,, there is a lot stored at 90 that's not usable and adds to hose/size demands.
I see a lot of focus on 3/4 mains but its wasted especially on 2 stage if we are doing it due to the fact it will help performance. Almost all the line loss is in the secondary after regulation and with a hose and directly proportional to distance.
A 1/2 hose will help a 1/2 air gun if it isn't being served but once we exceed the need its all irrelevant and allows movement for the operator thru a 50 ft 3/8 hose.
I do have a section of 1/2 and have bypassed it for 3/4 gun work and if I added a 1 inch gun would try to shorten the hose to 25 ft.
Same with home setups, need super poop, chop hose in half and up pressure to gun for cheap with 1/2 the pressure drop.
Maybe 8 or 10# depending on a couple factors but changing the man from 1/2 to 3/4 for 40 ft on the main,,,, .3 difference.