We have never had a problem. As soon as you board, go to a kiosk or a diningroom and make specific reservations. If in a suite, go to your butler aka retreat host, or the suite lounge and the host will make for you. We prepare a list of restaurants and times, to avoid any issues. Only once had an issue on New Years eve years ago on the Edge. We usually take the unlimited plan. Even if in a suite, prefer the speciality restaurants especially on the Edge class and M class ships.