Should the restaurant still try to reserve table for those regular customer groups, who have had 2 consecutive failed reservations.
Or the restaurant would not try to reserve tables once it is not able to reserve them 2 consecutive ticks.
No, the restaurant stops trying. Once the group has two consecutive failed attempts, it is out of the simulation and there is nothing left to reserve for.
After two consecutive failed attempts, which are either failed reservations, failures to be seated by the waitstaff or the whole group leaving the restaurant because no one was served food, they do not visit a restaurant again.