Now why would you want to do that?

And in close-up:

– Rendertime went from about 4 minutes to around 6 minutes.
– It looks horrible to mix two Principled Shaders. And: no, you can’t use only one Principled there, because:
1. The Principled Shader has Fresnel built in and you have no control over the roughness of the Glossy and also the Roughness of the Diffuse should not be dependent on the Glossy Roughness. (At least not in this shader.)
2. The Glossy Node has a different Color than the Diffuse Node!