I don't think the tournament is going to be resolved in just single extra round and that'd basically mean you'd have at least 2 instances in last 3 episodes, or realistically in 2 eps with final episode being some sort of epilogue. So that'd be 3 tournament events in 4 chapters (13 being exception) which would easily lead to overload fatigue and left very little room to give proper focus to the book contest. Not to mention other bits, including potential Gillian storyline, slutty Holly and/or Alison getting it on late with Ian, Louise relationship and, of course, Ivy :hidethepain: Oh, and Lena/Stan as well, Billy's photoshoot, etc and so on.
(i doubt Billy's boat is going to be also in Ch.13 considering it is after Seymour's trip. It's more likely it's either Seymour trip or Lena gobbling BBCs in her spare time, with Billy's photoshoot being potentially in Lena's half of ep.14)