Well, that kind of all makes sense.

It appears the living/dining room layout on your first post contains at least 25 light sources -- not counting the sun.

Not sure how you count 25 light sources. I had ceiling lights turned off. The kitchen light has 4 light bulbs. The bedroom light has 2. The bathroom has 1. The living room (behind the camera) has 7 and there's one more light in a lamp behind the camera. That's 15, not counting the sun.

Maybe I'm missing something, but thanks a bunch for the explanation.

That would help to explain why the photos taken, shown in the other topic I linked to, would take so much longer. I had ceiling lights turned on, plus at least 40 more lights, plus the semi-transparency of the pool water, plus all the glass.
Off the top of my head I'd guess there's about 30 to 35 default ceiling lights, on top of the lights I added.