The other thing people seem to forget is that the fall season runs from some time in September to some time in May. That's give or take 36 weeks. The longest episode run for a network show is about 24 episodes, usually 22 or so, but let's use 24. That's still at least 12 weeks of reruns. Even if you take 1 at Thanksgiving and 3 at Christmas/New Year, that's still 8 weeks you have to take off. So they plan them around other shit that typically kills ratings...like the Olympics. That's how it has been for years, I never understood why people seem to think it is suddenly something new when they notice it for a show they like (or don't like if you're Astro).