I've been watching the first two seasons of Justified and the first three seasons of Leverage and have realized something that may well have been obvious to everyone else. *laughs* That the first seasons of both series (and looking back on it Buffy, Serenity, Dr. Who, Mushishi, Bleach, One Piece and other series I've loved as well) starts with one episode stories, complete in and of themselves, but by the second or third season, the stories get more involved, spanning multiple episodes.
Characterizations get deeper with time and with both actors and writers getting to know them better.
The thing that strikes me, though, is that it works that way with my writing, too. That I do far better when I do a lot of short pieces with a character, getting to know them, per se, and then getting on with their bigger stories when I get to know them. I like realizing that they're much stronger if I do write the shorts, first.