I do 360 degree panos by taking 3 panos of 21 photos (roughly 120 degrees apart). 4 panos are over kill. Thanks for the hint how to take the two nadir panos (90 or 180 degrees apart?).
One more hint: the Spark fixes exposure for each pano, but not in between. Exposure can be equalized by good pano software, different exposures are ok. But you need to MANUALLY fix the white balance if you want to combine several panos.
Last hint: 91 photos take a lot of time! I therefore use Sport mode to fly straight to the mission point (if far away). And ignore the occasional RTH warning during the last few images ...