Heroes divided the year into two "books". The first one "Book 3 - Heroes and Villains" shown during the Fall of 2008 was a mess. The concept was to offer complex questions about what makes someone a hero or a villain and shake up our concepts. It sounded good but it got tiresome fast. Worse, the writer threw in a number of elements from the first season in an effort to recapture its feel. This didn't work at all. The visions of the future and quests to prevent a coming Apocalypse have been done too often.
NBC agreed and brought in a new writing staff. The result was a fresh approach with no time travel or visions. Book 4's best moments were the first few episodes with groups of agents taking down the heroes and taking them away to some sort of holding facility. It bogged down a bit at the end as Sylar changed sides a couple of times and went through an identity crisis. His argument with his "mother" was a classic bit that made Norman Bates seem normal. The conclusion set up for the next book and Sylar's eventual return.
Lost recovered from its slump a couple of years ago and had a season that seemed far too short. Where Heroes dropped time travel, it was the major point of Lost with half of the cast stuck in the 1970s.
Structurally, Lost's season was divided into two parts. The first part was the return to the Island for the ones on the mainland. Meanwhile, the ones who were left behind went through a number of time shifts and cast reductions. By the end of this arc, the survivors of the original crash were down to the core cast (plus Rose and Bernard who retired).
Once the time jumps stopped then we were back to something like the original format with an over-all plot plus flashbacks for a specific character showing how he came to the island.
Several questions were resolved or at least explored in more detail. We now know what the huge statue looked like. We saw the plane crash and got a glimpse of Daniel's group before she shot them. We also got to know the Dharma Initiative. We found out why the original hatch was built. Most important, we found out that the mysterious Jacob is a real person and has been near when ever important events happened to the core cast.
The last two season have been dominated by the fight between Ben and Widmore. The last few minutes of the season finale set up for a larger conflict between Jacob and his unnamed rival.
A couple of other shows are worth mentioning. In its first season, Chuck was fun but seemed like it could have been better. In its second season it was better, finally living up to its promise. After keeping fans in suspense for weeks, NBC renewed Chuck, at least for 13 episodes.
Dollhouse has an interesting premise. The star is a different person every episode. The first season was interesting but it will be difficult to keep it up. The first season featured two plot arcs. The first was a detective searching for the Dollhouse. This was wrapped up by the season finale. The second arc concerned "Alpha", one of the dolls who went crazy after being given multiple personalities simultaneously. Alpha escaped se we probably will see him again. Dollhouse was renewed but with a reduced budget.