Did not work at all for me. The shoes seemed to have stretched when I wore thick socks with them and applied the solution VERY liberally (must have sprayed like 5-6 sprays in each shoe on both front + back) but when the solution dried up, the shoes were back to their tight uncomfortable fit. I have repeated it 4 times , tried with both thick socks and also by leaving scrunched up paper inside my shoes.

I guess this would work depending on the type of leather you have, for some shoes the leather will only stretch a very little.