Every time you do a compass calibration, you risk having a terrible calibration due to interference from things in the environment you did not see or did not think about, or even stuff in your pocket. The result of that, if the calibration appeared succesfull, at best will ensure your phantom flies fine below 10ft and right above your calibration point. Exactly where it doesnt really matter as you could easily switch to ATT and take control.
But as you fly further away, especially beyond line of sight where you become 100% dependent on the compass to work, and where you are far away from the source of interference you calibrated with, Bad Things may happen.
So I would absolutely advise against calibrating on each new location; unless that location is 100's of Km from your previous calibration, or you did it a long time ago. If you did a proper calibration recently, and on a new flying site you notice toiletbowling or you are getting compass errors, simply dont fly there (or use ATT only and set failsafe to autoland rather than RTH).
But as you fly further away, especially beyond line of sight where you become 100% dependent on the compass to work, and where you are far away from the source of interference you calibrated with, Bad Things may happen.
So I would absolutely advise against calibrating on each new location; unless that location is 100's of Km from your previous calibration, or you did it a long time ago. If you did a proper calibration recently, and on a new flying site you notice toiletbowling or you are getting compass errors, simply dont fly there (or use ATT only and set failsafe to autoland rather than RTH).