First, just to mention since this was recent, I feel like the date change for the AC was a good call for organization if nothing else. Otherwise, I don't really have a lot of criticism about the system in general, really. I like that it's flexible which helps a lot, even if it spans over two months since the game can be prone to dry spells for long times.
One thing I know came up on an AC before, but it would be nice if we had the option of posting WIP threads until the AC officially closes? I understand the reasoning behind entries that don't count after the AC post itself goes up. But since the post IS open for a week, having the chance to finish threads properly for that week until the post is closed might be helpful for those who need a few comments or need to get a hold of someone to help with those comments.