12 minutes ago, Dex said:
Ultimately you can't ever have complete evenness because what's in the pan is effecting it as much as the coils and the pan itself.
This is a non sequitur. You can't have complete evenness because of the Second Law.
It is true that food in a pan Affects the pan's evenness, but (for homogenous contents), in predictable ways. For viscous and solid foods, and overall, measuring evenness of empty Pan A on Hob B is quite useful.