The tables of 6 do make life easier, but the rule would also be the same for 19 teams, and that could be as simply run with 18 judges, 3 tables of 6, with each of the 3 tables scoring one extra entry on rotation.
The bigger difficulty is getting the turn in table person to understand that rotating the teams amongst the tables is as important as watching the clock and relabeling the boxes.
Just my opinion!
"There is no such thing as a little garlic." A.Baer