flew a phantom for years, new Mavic this week. Latest firmware, no errors in the app. Flew for a bit today, no issues.
To calibrate or not?

If everything is working fine and no system prompts to calibrate, then all must already be in good calibration. No need to do until required either by system prompt or unstable flight needing investigation.

You can check parameters in your app for both IMU and Compass, if they are ok no need to calibrate.

The most important thing when calibrating the IMU is to keep the aircraft level in a flat surface and make sure to cool it down first when calibrating the IMU. Please pay attention to the message from your app and if the APP requires you to calibrate, please follow the instructions in the APP. Here are some scenarios that we suggest calibrating the compass:
1. When compass data is abnormal, and the Aircraft Status Indicator is blinking red and yellow.
2. When flying in a new location, or a location that is different from your last flight.
3. When the aircraft moves erratically during flight, i.e. the drone doesn't fly in straight lines.
You can go this route: MC Settings--Advanced Settings--Sensor--Compass--calibrate.

don't fix stuff that works,

Happy flying

They recomend calibrating compass if you are in new location. This is because magnetic north is not true north. The further north you live, the more serious this effect is. I would calibrate the compass, not the IMU, but make sure to do a good job of it. In other words don't be near steel. (This means take your keys out of your pockets and make sure you are at least 15 feet away from your car etc)

Mine hasn't been calibrated since it came out of the box.  I'd say China is a bit far removed from Nebraska USA, so I don't buy the calibrate when changing flight location idea either.  I'm assuming it was calibrated before it was put in the box, and all status indicators are still green.

AG0N-Gary Posted at 2018-10-7 08:53
Mine hasn't been calibrated since it came out of the box.  I'd say China is a bit far removed from Nebraska USA, so I don't buy the calibrate when changing flight location idea either.  I'm assuming it was calibrated before it was put in the box, and all status indicators are still green.

https://goo.gl/images/sRn5VS Check out the earth's magnetic field of compass zones.

I'm very aware of the (changing) variations in the location of the magnetic field.  In the 28 yrs I've lived in this house, the deviation has changed from just under 13 degrees to 8 degrees.  The fact remains, the Mavic has not called for any kind of calibration since I purchased it new - and it is very stable.