It's a little bit of both! Since each argument must be unique, it's preferable that each argument submitted focus on one main point in particular to leave other points open for others to use in their arguments, meaning that covering all the bases will also lead to a decent number of arguments. However, overall group participation is also important, so if a character would not be able to come up with a new argument but would be able to support an existing one, that's just as good.