The Chuck writers were brilliant in their fan service in that regard. And it's not only the season finales, they were always on the bubble and never sure if th

The Chuck writers were brilliant in their fan service in that regard. And it's not only the season finales, they were always on the bubble and never sure if they'd get the back-6 or back-9 of a season. Because of the uncertainty, there are generally 2-3 episodes per season, around either episode 9 or 13, and then including the finales, they would work as series enders.