Back in the 80s when I was a poor grad student I would apply a thin coat of Shoe Goo to the heels of a pair of new shoes (whenever I could afford them) to make the shoes last longer. I would just keep applying a thin coat whenever the old coat wore down. It worked. The heels never wore down. Can't say the same for the cushioning though. Has anyone else done this to get more mileage out of their shoes?
I do that to my Nike Air Triax TCs. They don't make them any more so the pairs that I have are all I'm going to get. I tend to wear down the outsoles all the way to the midsole long before the cushioning goes.
I put Shoe Goo on the outsoles to keep them from wearing down. Lasts about 4-8 runs per shoe before I have to re-apply. Allows me to more than double the mileage I normally get out of a pair of these shoes.
I cut pieces of heel rubber from my shoes before tossing them. Gluing these on wear spots lasts much longer than Shoo Gu alone.
Many will say that this is just asking for injury. No problems for me so far getting 1000+ miles per pair. I think the greatest threat of injury is from the razor blade when extracting the rubber.
I use thin veneer sections from old furniture, glued on, to make my shoes last longer. Just don't walk on your Bela wood floor with these shoes, they'll scratch it.