Geometry is only a part of the problem; much more compute goes into lighting and textures. Also scenes rarely span enough orders of magnitude of physical scale

Geometry is only a part of the problem; much more compute goes into lighting and textures. Also scenes rarely span enough orders of magnitude of physical scale that the differences in precision matter (except may when using FP16). Finally, you probably can accept reduced precision for faraway objects (usually the camera is at the origin).