The best series seem to begin their peak at Season 3. The writers would have enough background, set-up, exposition and depth of character to start cooking with propane and propane accessories. By the end of Season 3, there’d be some kind of climax involving all of the main characters and there’d be some long-lasting repercussions. In other words, Season 3 is the time to start cashing in and, if the writers play their cards right, it can last 4-5 seasons (and keep going beyond that, even if it's rarely as dramatically interesting).
This is where Justified sits. Season 3 was incredible; it was just below the elite level of television, but well above the fray—and it looks like they’re ready to build more, greater things.