For example, if I would want to at some point disable one of the elements, like roughness or metallicness in one of the instances of the layer, but without touching the parent layer.
I would just un-tick a checkbox and the whole node wouldn’t have to pass through the blending process when I decide to disable it in a specific material instance.
Right now I’ve come up with switches in blend function, but it’s not the ideal solution since instructions are still growing with each layer.
I hope I explained myself…
Here is what i mean: