Operational efficiency depends on having detailed, up-to-date information.

How long have the tables above been seated? Which table above will most likely become available next?

That can’t be determined from pennies on a piece of paper. Servus makes it clear that table 323 has been sat for an hour and will almost certainly become available next (and fairly soon) so you can be ready to seat your next party of six.

You could try to have host staff capture this type of information but it’s time consuming and error-prone. Besides, wouldn’t you rather have them focused on serving your guests?