You are mistaken.
Calibration is absolutely necessary, after mounting the module in its final resting place. See this post for how far off magnetometers can be, and what to do about it: Correcting the Balboa magnetometer
You are mistaken.
Calibration is absolutely necessary, after mounting the module in its final resting place. See this post for how far off magnetometers can be, and what to do about it: Correcting the Balboa magnetometer