So I took the winner from our first test, the Grille, and tried different building types. Even within buildings of the same type, the results isn't always the same. I ran 4 trials. Here are the number of rounds of 150mm that it took to destroy each type of building for each trial.
TYPE OF BUILDING: ROUND1, ROUND2, ROUND3, ROUND4
shack: 2, 2, 1, 1
small light: 2, 2, 1, 2
tall light: 3, 4, 3, 4
small heavy: 2, 2, 2, 3
tall heavy: 8, 8, 8, 8
The morale of this story is that the taller buildings of either type take more abuse.
I also tested to see whether there was a multiplicative effect when multiple tanks shot at the same building. There is not. A tall heavy building still takes 8 rounds even if those rounds come from 2 different tanks. Although there is clearly a rate of fire bonus so the building drops sooner when you use more tanks.
Since I also got ROF info from my tests, I thought I'd share that also.
Grille 150mm - 2-3 rpm
Hummel 150mm - 2-3 rpm
Wespe 105mm - 3-4 rpm
StuH42 105mm - 4 rpm
Brummbaer 150mm - 2 rpm
Tiger 88mm - 5-6 rpm
JagdPanther 88mm - 5 rpm
Nashorn 105mm - 5-6 rpm
StuGIIIG 75mm - 6-7 rpm
Any other tests that you are interested in?