A lot of the holistic security work I have done does try to work out where organisations are relative to peers in industry across all security disciplines. Physical security is often a finger in the air, do we look better than the building next door, kind of thing.
Documented best practice does not appear to be as common as in other areas of security. I think it is because people feel like they understand physical security better than some of the more esoteric branches.
Social engineering / breaking and entering are my two tools to try and persuade organisations to improve here.
I hadn't seen the German BSI docs before, though - worth adding to the list.