Is this a texture scaling issue?

I’ve created the following material (with a great deal of kind help), but my landscape suffers from blurry images at a distance, that also have some white speckly bits that I cant paint over/out.

Material:

Landscape at a distance:

What I’d like it to look more like:

I’m using a 3dworldcoordinate node as opposed to UVs as they stretched my texture, but how do I fix this issue?

Do I need to add a constant value to one of the inputs in the 3dworldcordinate node to affect the output scale of the landscape material, I’ve tried a couple but its not having much impact.

I’d appreciate some help.