circusmonkey
Next why would you even bother with 10 separate materials for your rocks. Instead the Houdini approach is to have 1 material and 10 different diffuse maps either randomly applied via an override at the object level or better still just have the shader look up a map randomly.

That's how I've set it up in my example file. Local overrides in Mantra are bliss.

I guess this is where the workflow differs a bit from the softimage way.

In my case I am using zbrush so each rock has a different diffuse/disp. I also like the possibility of tweaking the materials separately. In this case the rocks are on the beach, some have strong specular (wetmap), some don't. Some are close to camera, so I need more detail etc. I guess another route to make it a bit more procedural is to use tokens ROCK_01>ROCK_01_MATERIAL. etc

I could have done it in one material, but don't think it really matters as much to me at this stage (just learning as you can see).

However, in a commercial pipeline you need to give all 3d artists some freedom, I couldn't possibly police every single shader, for every single asset with displacement to make sure the Occlusion shader is wired in correctly and with the correct values. You can see how that could very quickly turn into chaos.

This is the beauty of partions overrides in softimage, you plug the AO as a surface override on a “group of objects” level, it doesn't care what shader each object has applied locally. This is extremely important when you want to keep displacement values consistent across all AOVs.