The zig-zag lighting pattern is based, as best I can tell, on a misunderstanding of dynamic photo-inhibition. Dynamic photo-inhibition (DP) is a natural process where protective xanthophylls (diadinoxanthin and diatoxanthin in zooxanthellae) absorb blue light and shunt it away from photosynthesis - in other words, it is a pressure relief value when corals are exposed to too much light. On natural reefs, DP kicks in as early as 9 am when light intensity exceeds the amount needed for a maximum rate of photosynthesis. Hence, the rate of photosynthesis begins to slow and prevents damage to the zoox/coral. In the afternoon, as the amount of light begins to drop, and the amount of light needed for max photosynthesis is not exceeded, the pressure relief valve is no longer needed.
I think some believe the ramping up and down of light is some how needed and beneficial. Granted, there could be situations where an aquarist is blasting corals with light intensities approaching natural sunlight and a reductions in light would be beneficial. But I think this would be the exception, and not the rule.