In television, how a series is going to proceed has to be kept a mystery. I remember reading about how Chris Carter (series creator of the X-Files) had scripts printed on colored paper -- because type on colored paper cannot easily be photocopied. You don't want the whole world to know how the season is going to proceed. It's really just a big deal, especially if your pool of writers racked their brains many many nights just to make it seem different. Imagine the horror of suddenly knowing that the other series in another network made use of a device or storyline resembling yours (so eeriely similar it could only be..) What can only be more appalling is when the actor in your series does a promotional interview and begins to unravel three seasons' worth of plot twists. Mystery no more. You can only wish to decapitate the thoughtless guy. Blech.