The paper that is referenced by Craig is a bit of a problem in that it deals with the direct cause of flare by extreme lighting conditions (mostly backlit) which any photographer who has captured images in nature with strong back lighting realizes how bad flare can get and how difficult it can be to adequately deal with it. I'm old enough to remember the old Kodak leaflets that accompanied their film that noted best images can be produced with the direct light source in back of the photographer. As others have pointed out the extreme case does not prove generally applicable nor does it invalidate ETTR. ETTR is extremely valuable as long as we understand how to apply it and what the limitations are. In the end the laws of physics are immutable (the confirmation of the pending discovery of the Higgs boson not withstanding).