Practical application for this?

This may seem strange, but I backed into this in a strange way. I drew a few wavy lines and use the blend tool to make more and distribute them. I looked at it for a minute and thought how much it looked like elevation lines or a representation of the flow of land.

I thought that this might be a way to be a guide for myself on where to apply highlights and shading to give the illusion that the landscape is changing elevation.

I have attached the xar file that represents my doodles and is intended to give you a rough idea what I am talking about. (The lines layer is hidden, just turn it back on to see what I mean.)

What I am wondering is: Is there a practical application for what I found by accident? Do you pro artists out there create guidelines like this for yourselves to bring continituity to your drawing for shading or other applicaitons?

Just wondering,

Eric