The drone comes from the factory with a properly calibrated IMU and compass and they don't go out of calibration unless involved in a big crash or you add or remove parts to/from the drone.
In >10 years of hard flying, I've never had to...
It's not normal to have to recalibrate the compass or IMU.
If there was a problem with those, he would have already noticed that and the app would have advised that recalibration was necessary.