I voted 4 because there are many families onboard and it is very possible that one parent will get the seats while the other is with or getting the kids. Also many couples are together and one of the group may want to get to the theater before the others.
Definitely do not feel that a person should be able to save as many as they want.
Star Princess 2005, Sun Princess 2005
Caribbean Princess 2006, MSC Lirica 2006 , NCL Pearl 2007, Majesty of the Seas 2008, Carnival Destiny 2008, MSC Lirica 2009, Carnival Valor 2009,Carnival Legend 2010, Carnival Liberty 2010,Carnival Fantsay 2011,Carnival Valor Feb 2012, MSC Poesia Dec 2012, MSC Poesia April 2013