A few series that have good places to stop watching before the series actually ends (no spoilers)

This post isn't about shark-jumping, which is when a show has gone on too long. It's about when the important arcs have been resolved, and while what follows may have strong moments, the show is not as satisfying overall. Buffy the Vampire Slayer has two good endings. From a purely esthetic point of view, the third season, when she graduates, has the perfect ending. But the end of season five