Yeah but in a one on one duel the writers usually agree to a predetermined end point (in my case usually after 20 posts each). The duel has a beginning, a middle and an end. Each writer is forced to make the most of the posts, forcing quality over quantity.
Second, in a free for all, how do you propose the posting rules? As you know, some of us, are here most of the time while others have school, work, etc. Would there be a fixed time for replies? A posting order? If not then the advantage goes to the person who can speed post.