During this 'compass needs calibration every day' period, has you always been working in the same general region? Did it keep happening after moving far away from that area?
I'm just wondering if there is any kind of interference in the area...
My thinking is that while the app might not always request the compass calibration, it is such a simple and quick procedure that there is no harm in doing it anyway. DJI recommends compass calibration for any drone that has been transported over...