Originally Posted by jbrians

TECHNICALLY speaking, chains don't stretch. They wear and as a result of metal loss on pins and bushings they get longer. Since the wear happens for the most part when the links are under load and BENDING/MOVING, I would expect to find wear on the arc of the chain when it changes direction as it starts the arc around the sprockets. On the jockey wheel side where you get the reverse direction arc happening there isn't much tension on the chain, hence the wear would be minimal...(of course, I'm assuming the chain is being looked after properly so the spaces aren't full of grinding paste)
As an experiment, I took a chain at the full stretch limit and flipped it over and ran it inside out. It BEHAVED like a chain that was within tolerances. The wear on pins, etc. is now on the outside arc of the chain and that's not where the tension is now. I'll report back with mileage on the chain over the course of the riding season.
My guess is, I can't expect double the mileage but I would think I can get another 50% at least.