I target trying to get the rear to lock just after the fronts to help keep the car from wanting to rotate. The rear bias should be set with on-road testing and I am not seeing the value of checking both front and rear pressures at the same time with a gauge. Rotor diameter, tire size and weight distribution under heavy braking [and other factors] all vary from car to car, caliper pressure is just a value at that point.

The front pressure is what the front pressure is, adjust the rear. You need an m/c bore adjustment if you cannot lockup the front.