Consider the networks point of view. -I'm predating my years a bit here so forgive any historical inaccuracies- But remember when the Jets played Oakland and the game ran long (1968 Heidi Bowl)? They decided to leave the game and air the movie Heidi as listed. Long story short the game took a major turn the team that was loosing ended up winning and the public outcry for missing it was phenominal.

Besides, isn't it the networks fault that the show times are pre-empted and not just the advertisements?

I know, I know; why even run a network it you can't become fat dumb and happy from advertising dollars.