pros & cons of layer shader arnold

[conomara]

Hello

First thanks in advance for any info.

Are there any pros and cons of using layered (mix) shaders that i havent thought of, Specifically when it comes to physics and energy conservation etc

Pro:I know layered/mix shaders are easier to set up and reuse

Con:I know they can be expensive esp if the mask has a lot of none zero or pure white areas

 

Im assuming the blend function is energy conserving here when using the mix/layered shader

Do the layered/mix shaders off a better solution over just using masks behind to the standard shader to for example mix in dirty areas over glass, or wet/shiny areas on wood or whatever the mix maybe be?

 

Any other thoughts and musings on this welcome as well

Its prob not a specific arnold question, im interested across all renderers

thanks

Conor