The formula is a very simple mathematical equation the represents flow. It is 100% correct. The VEs assigned are probably correct enough.

But here is the part people don't understand or struggle with. That formula has nothing to do with what is the best size or best carb for an application or needs of the car owner.

The formula assumes that the 1.5" hg pressure drop that the carb (4bbl) is measured/rated at is the "right" or "best" dP. It seldom, or maybe never is.

In real life, the lower the dP (bigger carb) you can get away with while maintaining good fuel delivery, distribution and atomization, the more power you will make.