This is my biggest problem with iTunes: “iTunes has stopped updating this podcast because you haven’t listened to any episodes for two weeks”.
If I'm not extremely careful it can lead to my missing episodes of In Our Time!
I've been looking for a hack that would force iTunes to wait at least 8 weeks. This Apple discussion thread points to a blog post discussing a Doug's AppleScript that forces a regular bulk update.
Be nice if Apple fixed this, but meanwhile OS X iTunes users have a crude workaround ...