Thanks for the replies.
I can see the argument for having all stages on one side, narrower profile for wrecking, caving, scootering and maybe even in a heavy current.
I'm only diving a single stage, just for accelerated deco ATM and I have heard the quote of "Rich on the right, Lean on the left" which was why I asked the question. Just seemed strange that having been taught this mantra I'm then shown how to rig my deco stage, richer mix, on the left.
With a single stage I'm not worried about it too much but was curious and wondered what others felt.