When I'm not diving my PRAM double hose, I dive a US Divers Conshelf 14. The port arrangement on the 14 is such that the HP port is on the right side. Going counter clockwise (as seen from behind the diver), the next port is the primary LP, then the LP inflator and finally the LP secondary. This is the only practical way to use a Connie 14. If you try to orient the HP on the left, then the inflator and secondary hoses are pointing down and have to make a 180 degree turn to be used. I suppose one could use swivels but that adds failure points.
Further, the 14's port arrangement is perfect for diving doubles with an old-fashioned manifold having one regulator post in the center. All the hoses sprout upward, away from the tanks. Since the 14 was designed for the military, this makes sense.
Personally, I like having my SPG on my right and having the secondary on the left makes it more comfortable for another diver to use. A little talk before the dive should be sufficient to let your buddy know what's what.
As far as using the secondary myself, it's on a three foot hose and positioning the reg for my own use is simple and easy. I have often wondered, ever since the whole secondary/octo thing showed up on the diving scene, why the secondary was traditionally mounted in such a way that is so awkward for air sharing.