I'd hesitate to compare anything with less than 20 episodes in the same list as regular series which need to go on for many seasons. Could Spielberg have maintained Band of Brothers at the same level of quality if he'd have tackled the whole war and done four or five seasons?
Twin Peaks is a good example - terrific first season, then it fell off a cliff. If one great season is all you need, then why not put Heroes and Prison Break on the list, too?
Twin Peaks is a good example - terrific first season, then it fell off a cliff. If one great season is all you need, then why not put Heroes and Prison Break on the list, too?