At the moment Im using Blender 2.78. Im using Blender Guru's PBR Workaround for materials. In the scene I'm working on I use textures from Poliigon.com. In the Poliigon help guide it says that reflection maps should not be used in a PBR workflow. So that socket will have no node connected to it. Is it then up to me to estimate the reflection value for the material? That doesn't feel right.