And in my case I only do it after firmware updates or after adding/removing hardware. I don't routinely calibrate every flying session. But I do fly a test hover at 10ft at the start of the first flight of the day to check for a solid hold and normal reactions to controls.
However often you choose to calibrate the important thing is to do it in a good "safe" area - wide open, not near any ferro-magnetic materials (inlcuding below ground) or other sources of potential concern (like next to your car, metal railings, etc). It's possible to cause a problem that wasn't there with a bad calibration. Been there, done that![/quote]
i was planning on doing it in my back yard because that is where i want my home point to be. buy i have a huge trampoline right in the middle. that has a lot of metal. should i not do it there? no matter where i go in my back yard i'll be within 30 feet of the trampoline