I can't really comment on your system but I think in general light requirements are slightly inflated.
From my own little tank with 52w of PC light underneath which I have Porite coral and a couple of little pieces of digitata that as per rule of thumb have no business being under such low light. The digitata is certainly growing and the porite coral looks fine, it even has regenerated a bald spot where my sexy shrimp were picking at it when it was first introduced. Will they survive? Time will tell.
So yes from my limited experience I think light requirements are inflated but that is probably due to ensuring greater successes.
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