There's this cool trade off between how much you can charge for commercials, and for how long you can take up an audiences interest. The cable shows have longer intros. I think this is because of how expensive it is to shoot the footage, but they know they can capture the audience for a full hour, so they'll grab any way to get to that full hour cheaper.
Cartoons are an extreme example, being very very expensive to animate, many cartoons in Japan have an intro of almost 15 minutes, then ~25 show, then 5 minutes outro! (these are cartoons targeted at teens/adults)
I was going to add this to the list, because I think the Homeland intro is really interesting and well done. Usually I fast forward through them, but I notice something new everytime with this one.
You have some shows, like The Good Wife, that use a five-second title card.
https://www.youtube.com/watch?v=1rOhzdWZS7E
Some have more elaborate titles, but still only go 15 seconds (e.g. The Mindy Project)
https://www.youtube.com/watch?v=HarfyFwRfhA
Compare with an 80's show like Dallas, where the credits went a whole 1:10! That's like lost real estate for two or three commercials!
https://www.youtube.com/watch?v=1iYjgMygIag
And Twin Peaks, which went 2:36:
https://www.youtube.com/watch?v=X2lkvrMa27c