Never considered that but maybe its a worthy idea. To me it seems like a chain will lose its lateral stiffness long before it has "stretched" enough to effect its engagement with the sprocket teeth. The loss of lateral stiffness makes it harder to shift - especially with the front derailer. It could very well be that even after a chain has served its life as a drive chain, it may still have a lower pitch than an older sync chain. I've never checked the pitch of our sync chain. I may try this out & see if it is much worse than an older drive chain.

This brings up another controversial subject - rotating tires front to rear. A tire that may be a bit sketchy on the front may be OK on the rear. Tires rotate front to back. Chains rotate right to left.