They will limit the number of late lunch ADRs so the waitstaff can set up the tables for dinner, probably just use one section for the late lunch people. There is usually a shift change between lunch and dinner too.
We had a 2:45pm lunch a while back and noticed that after 3pm no one was seated. We were not rushed, waiter said we could take our time, but they were setting up vacant tables around us for dinner as lunch patrons left. When we left there were people in the waiting area checking in for dinner ADRs.
So they don't completely shut down, just use part of the restaurant for late lunch and seat early dinner ADRs in the other sections.