I set the tension on the elcetric screwdriver to bring me close, then use my ears to wiggle it closer or to what I like.
A poorly machined drum lug + Trod, added to a spring with an incert,..wont give each lug the same properties. Pro level drums will. Single tension drums are even more out of tolerances. Calf heads,..good luck !!
I can see uses for these with learnning expieriences, Great for viewing the differences in range.
They`re good for new heads and great for telling you your old head needs to go !!
I still have my guitar tunner and use it, but my drum dial was hit down left field line and hooked foul at the smoke stack !!