With respect, calibrating compass compensations is in fact very important in FAA approved aircraft. It's part of the inspection checklist signed off by the licensed mechanic.

My flight instructor once switched off the electricity to the airplane's controls and radios and told me to land. At an airport with a control tower. Using the magnetic compass, airspeed, barometric altimeter, RPMs, that's it. Nothing else works without electric power. There's a whole procedure for doing all that. Being able to navigate safely with an old-school magnetic compass is life-critical.