light length

I just had a random thought/question about lighting and please correct me if I’m wrong: Let’s say that your tank’s chemistry/flow and everything is on point. Will having a longer photoperiod of LEDs that don’t have the best PAR/PUR do the same as lights with high PAR/PUR lighting that is only on...

How long do you run your lights (full intensity) each day? I turn my full spectrum on my tank before I got to work, and they stay on for about 8-9 hours, then when I get home I switch them to blue lights for about another 1-2 hours before it's lights out... Is this to long?

I have a custom 100G that measures 41" x 24" x 24". How long of a fixture would be good enough to hit the whole aquarium with proper light for coral growth? 36? 48? To me 48 seems like overkill, but then again I am still trying to figure things out;)