I'm not real big on the "extras" in DVDs---commentary, and all that---but in "The Shield" DVD, I did listen to some of the commentaries, and it gives you a great insight as to how the writers start story lines, then decide it won't work, or it will distract from some other story line. That was obviously the case with the David Palmer "handshake" at the end of 2004's season where they probably thought they would pick up with that, and instead went a completely different direction, only to tie it back in (minimally) last season season.