There is no hold or timeline for story posting. After a story sent by author, it will appear on the site within 2 updates. If a story is rejected, the author will get an email notice. All story updates / new chapters will also be posted without any holding time.

Some authors simply lost interests to continue their stories. That's the only reason I can think of unless they decide not to send any update to this site. If you write an review on this site or send a comment to author, you may get the author to write again