I got nervous around the middle of season two. The story was wandering and I wasn't sure what the stakes were. Everything started to feel less... well... crazy. The season finale had to cram in a lot of plot to ramp things up again. Afterwards I listened to several interviews with the series creators. They described Season Two as having a three act structure. Looking back I can see it. I also respect how the characters can have multiple ups and downs without hitting the "reset button" and forgetting what they've already learned.