By doing so you are changing one dimension of the scratches, it's not an homogeneous change zeitmeister
That said scaling the UVs from within the host application should work too, being procedural this shader does use actual UVs. In this regard it is best to multiply them at their source in the shader, wich is getTexCoords(0)
. The multiplier can be greater or smaller than 1.0 but it must be a float (dot something), integers will cause an error.
Once you have multiplied the input UVs like so, the depth must be changed proportionally. Divide the depth by the new multiplier and you should be done.
(0.0005 / mult) * etc
where mult is the float you choosed as multiplier for getTexCoords(0)
This way the shader will effectively be scaled proportionally.