My own problem with Season 3 is that after "World's Collide" - nothing really happens. The bulk of the story that was built up in S2 was over. It started off INCREDIBLY strong and then...nothing. Had they kept up or tried to maintain the breakneck pace established before that, then I really do think that season would have topped #2 in every concievable way. There are a few loose ends that are wrapped up here and there over the course of #3 - repercussions from "Space Invaders" and "World's Collide" for example - but outside of the Time sidestory that establishes the split it's mostly just random adventures here and there until we get to "Hun on the Run" which finally advances the true plot. Doing all that extraneous stuff to separate the Turtles wasn't even worth watching until Donatello and Leonardo's stories came along. No one will contest that "Same As It Never Was" is one of the best stories in the entire show - period - and everyone loved the second Usagi Yojimbo crossover in the franchise; while "Across the Universe" (the Planet Racers ep from that side storyline) is often mentioned as one of the worst.
I don't mind filler eps at all. Unlike the first four eps of season 4, its filler was fairly decent. But I think that a few of those episodes could have been cut up to maybe "Time Travails" to really make "Exodus" have had the same impact as the first couple storyarcs in the season (which it really needed).
The only problem Season 4 had in my eyes was that it had a HORRIBLE start compared to Season 3. The thing about Season 4 is that it was all world building. As a result - it expanded the TMNT 2K3 universe to what it is now. Problem is, while world building is good: it took forever to accomplish that. Everything past the first 4 episodes was good...but the arc as a whole took forever to actually get interesting and never
quite stood up to previous arcs. Unlike S3, plot points tended to be scattered in tiny bits. As a result - if you are a casual watcher of the show, it doesn't really seem like much is going on at all. That probably accounted for the massive ratings drop. To many people - myself included at the time - it seemed like a bunch of standalone unconnected episodes where nothing is really going on. And in a way, nothing really is unless you watch it all the way through.
They probably did that due to the breakneck pace of Season 2/start of 3 and their constant stream of multiparters and/or clumsiness of S3 fillers which is understandable, because after a while there were so many that if you missed an episode you may have screwed yourself in knowing what was going on. They probably felt that by slowing things down it'd make for better viewing, but instead they kind of hurt it, and as a result of people either didn't know what was going on and/or got bored with it. So they turned away.
This is true, but that is why proper pacing is paramount and partly why Season 5 seems to have been a success. You can do quite a lot and get a lot accomplished in 13 episodes. "Nightmare's Recycled" - while it was never produced - was a waste. As you can see - it's exclusion didn't do anything to harm or help the season in the least bit. Even "Membership Drive" as tame as it was - resolved the Nano subplot for good, tied into the ending in its own way, and still had the world building/filler quotient going for it. "NR's" slot could could have easily been used to expand "Enter the Dragons", but in an attempt to push the boundaries (on a character many people hate no less) it wound up biting them in the tushie.
I really think that if Season 5 had been 26 eps it would have hurt it more than helped it, not because of the episode count, but because of its pacing - as shown with Season 4.
Probably, but even so I'm hoping that after this and the mess that was FF they'll learn to use the episode count that they have wisely so we don't see these mistakes happening again. It's not like they don't have plenty of dangling plotlines to resolve from both series thanks to it.
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As a side note - besides the fate of The Rat King, Darius Dunn and the Dark Turtles, and the incredibly lackluster Torbin Zixx - what plots are leftover from the 2K3 series VS Fast Forward that have not been concluded or revisited?