it is far more common than you think. if you have a texture modified inside a band node (what i do every day) you will probably have to :Not at the moment, like I wrote before, the average value of the texture is estimated and used for a comparison with the glossiness threshold. But using not constant roughness sounds quite uncommon to me
tweak ----> debug view render ----> tweak ----> debug view render ----> tweak ----> debug view render ----> tweak ----> debug view render
until i found a good compromise between my large surface shader and cache set.