The dinning room didn't server lunch on most of the days in port. The buffet and specialty food station were open their usual hours. Dinning room Breakfast was servered every day except the last.
We never had to wait to be seated in the dining rooms and the service was almost always prompt.
It is a good idea to arrive about 5 minutes late for dinner though because a lot of people line up outside waiting for the room to open, but after about 5 minutes you can walk right in without waiting.
I was surprised about how dressed up most everyone was in the dinning room last week on the Triumph. I don't know if people in general are dressing up more, or if it was just the particular crowd on this sailing.