Rule of thumb....No. If it was done right, it was engineered....which means that each loop is laid out so that all of the loops are all equal in length. The farthest bays would have fewer "zig-zags" since it takes more tubing to get to the bay. The closest bay would have more "zig-zags" because it would require less tubing to get to the bay.
If it were me, I'd label each ball valve with a tag. Get a laser style surface thermometer and check the middle of each bay. Adjust each ball on/off and keep track of the results. The reason I say to check the middle....is because usually, the "runs" to the farther bays traverse across either the front, or the rear of the bays.
Slow work...but I don't know any other way????
