Most restaurants would prefer a booking of 2 to sit on a table with a max of 2 covers, to ensure that your larger tables are available for when that party booking comes in.
To ensure that simpleERB effectively allocates customers bookings to your desired tables first depending on the bookings covers, you will need to set up your "prioritize table ranking by covers"
Here you can see the table layout below has more larger tables than tables of two. To ensure that the tables or 2, 4 and 6 covers are booked first so that the tables of 12, 15 and 20 are booked last we need to categorise them in a bookable order.
The screen shot below for the setting (prioritize table ranking by covers) you can see that we have viewed the ranking for 2 covers.
You then need to add tables to the ranking table by selecting them from the "add table" drop down list.
You can then move them up/down the list in order you wish for the tables to be allocated.
Once this setting is in place, then simpleERB will know which of the available tables you would prefer this to be allocated dependent on it's covers. The more ranking options you input into the settings (example - 2,3,4,5,6,+ covers) the better and more efficient the system will work for you.
Remember you can always also add in your ranking by tables to add another level of allocation for bookings.
To check if you have set up your table ranking in your desired order for a busy Sat evening or a quiet Thursday lunch service, you can check your settings using the table rank check.