Yes it is a tricky thing to explain, and it is hard to explain "what's going on right now" vs. "what's going on through the day". People have a daily "compression" and "expansion" in their clock, and yet the main thing we haven't explained that the ideal case is when they cancel out and help you sleep when you need to.
If you shut off all the lights at noon, your clock would "advance" from the day before - as if you had traveled east. And if you kept all the lights off until noon, you'd "delay" due to seeing brighter light later in the day.
Normally these two regions cancel each other out, so ultimately we have to talk about the whole daily exposure.
Most of the heuristic advice ("see more light in the morning and less at night") is because most people with sleep trouble are "delayed" or late types. But this advice is not for everyone - many older people wake up earlier than they'd like, so they may need different advice.
You might notice that we focus mostly on "sensitivity" in the graph, and we're trying to hint at the overall daily response. But there are still some things missing, because it's complicated & hard to explain.
