Calibrating is not fixing or repairing or etc...., it just calibrate the compass system!
So if the settings in wich you calibrate are OK (no metal, rebar, concrete, cars very close etc etc ) than a calibration does not harm your / a drone, even if you calibrate for each flight.

Ofcourse its not neccessary to do that often, but it cannot harm your compass if done in a good place without any interference.

If you calibrate having magnetic interference at the moment you will calibrate that interference out of the system, but when flying than without that interference you will get compass errors and so on. So be very carefull when and how to calibrate!, do it good!!

Cheers
JJB

It shouldn't be necessary to do often, however myself and many others are experiencing that we have to it every time we fly.