Thanks nomuse... yeah, I should seek out and look at some of those scale modeller resources, good suggestion.

I've been deliberating whether to paint some control maps.... as much as I quite like what's happening in some places, using just the procedural spots and clouds nodes to distribute the rust etc.

As you're suggesting, a lot of the distribution patterns are not just mesh planar orientation based... but defined by all sorts of different physical effects... splash, spray, bouncing grit.

In the case of the army jeep, maybe some inbound shrapnel etc.

I wouldn't paint the diffuse... I don't think... but rather just a series of grayscale maps to control math blender nodes... maybe two or three different maps, one for each effect?

That way I can entirely adjust the actual color, etc, procedurally... just generally blend it in different ways. But I'll have the more precise, heuristic control of where different effects, and extremes of effect are happening on the jeep body.