KDR_11k you dont have to do every effect with the same shader. For example if you want rust on metal you have metal shader and rust shader and mask for the rust shader (preferably vector then it will be always sharp too)
I use this to some extent in a prototype game. I have a base diffuse layer and a mask to denote where the procedural shader is to overlay. It's a kind of 'mother of pearl' looking shader for vehicles made from a shell type material. You would be surprised at how much detail you can get with a 128x128 diffuse layer with…