If the problem is that no one will post in an open thread near the end of it's lifetime, a silly solution would be to automatically create an open thread every day with 10% probability. Now someone considering posting has no reason to wait for a future day to post because the expected lifetime of a thread is always constant, and is ~10 days.
Better would be to have a single thread "Open Thread" where posts older than N days would be moved to an automatically created "Open Thread Date-Date" post.
An even easier fix would be to remove the end date from open thread titles. When someone feels like posting a new one they just do that. This is a sloppy implementation of the first solution.
People will start a new thread just to bring attention to their post, while being immune to the criticism of "This belongs in the open thread"
This week's open thread is less than a day old, and has already accumulated more comments than the 15 latest non-open-thread posts combined. I fear the thread will wither and die before Friday.
Going from monthly to weekly open threads was a big hit. Should we ratchet up open thread frequency even more? Should we add more outlets for comments, or will comments inevitably expand to fill the available room?
Proposal for discussion: We follow a regimen of weekly blather threads for the next two weeks, then reassess.
Addendum
I posted a Links on Friday and a Stupid Questions on Monday. In the 5 post-days that they've been up, they've accumulated 32 comments. Based on these numbers, it seems unlikely that these topical open threads will relieve pressure on the main Open Thread and so I've stopped the experiment.