The point is you post all those threads in the first 2 days, and for the rest of the month those threads disappear in the Anime Discussions section or in whatever section you post, and nobody really wants to go out of their way to search for those threads and post unless they want to spam or increase their post count.
Also don't post a thread for each episode, especially this time. Katanagatari had 50 minutes for each episode so that was alright but this time each episode will probably be 20 minutes in length so there won't be a lot to discuss each time. Post one for every 3 episode. Plus, nobody really wants to post in 13 threads.