I guess I'm missing out on something. A shed isn't the length of the snake? it actually stretches that much?
Actually it does!

The example I gave is for my corn, and it seems that he is usually 85% the length of the skin. It is by no means an exact science. About the only thing you can really infer is that the snake isn't any longer than the shed. I've noticed my BP skin usually isn't stretched as much, but she also sheds in a different manner.