multitable tournament rules

[cyberer]

In our home tournies we employ a multitable tournament, but we do it where if we have 12 players, we have 2 tables of 6 and 6 and when the 2 tables reach 3 each, the 6 players left combine to form one large table and keep their chip stacks from the preliminary tables. I understand that this is not how multitable tournaments are traditionally run. How are normal multitable games structured?