So I had this thought about 24 during my commute today, when I should have been paying attention to the road...
So, I thought it was interesting that this season sort of had a bookend with Jack being asked the same question in both the first episode and last episode. Actually in basically the first and last fifteen minutes of the whole season. By Sen. Mayer in the premiere, and Renee in the finale, Jack is asked if he regrets the things he's done.
Now, Mayer doesn't use those exact words, but the implication is pretty clear, and Jack comes out and says in front of the entire Senate subcommittee and the world that he has no regrets. Twelve hours later, having had a seriously shitty day and literally dying, he tells Renee that he doesn't regret anything he did over the course of the day.
The 'correct' path of character development in books and TV and movies is usually seen as the character making some kind of change over the course of the story. Even in a single season of the show we recognize that this should be true. Bones, by the end of Season One, is already slightly less awkward and more empathetic towards others... Scully realizes that maybe not everything is as cut and dried as she believed... and I could go on and on but I'm sure that you could come up with dozens more without straining your brain even a little bit.
So, keeping in mind the bookend question I mentioned above, does Jack undergo any development of his character in Day 7? Does it even matter, or is Jack Bauer one of those characters that people don't want to see change?