Originally Posted by
superstar911
Seasons have about 22-24 episodes to last from September - May which means they need to strech seasons to make them last. They hiatus during holidays and some shows stop for a full month to allow production to get ahead (Heroes for example).
Fringe also airs post American Idol which requires 2 hour slots instead of 1 on occasions (but it seems to be more than occassional nowdays) and Fox are happy to expand because it's the top rated show on TV, after the Superbowl.