What if you put 2 planets on the the same coordinates?
That would be a very bad idea. Even if the planets got spawned well apart in the Z axis, since the gravity wells are actually cylindrical rather than spherical you would have great difficulty telling which well a ship was in (for game purposes, each well is completely separate and even if they overlapped you'd have to phase jump to switch wells still).
This would explain why jumping along the Z axis can be a problem. Thanks kryo!
Is there a recommended angle, not to go below on the Z axis, assuming that straight up and down is 0 degrees? to allow good fleet movements between GW's