You are very right, reference the SO differing from place to place. But if they are being diligent (not range Nazi's) a cover call gets a quick step back from most competitors, as it should.
"Diving under something" mostly, is not such a good idea, ricochets tend to skip along the ground, about 4" about, above it, yes, right, just were you are!
Way back when, when we first started shooting IDPA, in Canada, the Guy who started it, was an innovator (Sadist!) the common perception was that the gun would jam up (malfunction) if it was fired sideways, ejection port down, as in under a vehicle. The case will jump back in? to the port.
After the called for 4 shots, from every one? No, did not happen, your gun just got dirty (quite a bit of complaining about that!) but it was a good thing to know.