Cliffhangers need to be resolved. Gamechanging results need to be looked at. The Big Bad's plot or MOTF's rampage need to be put down. Differences need to be put aside for the moment. Mangled friendships need to be patched up, or space and time need to be given.
And most importantly, after all the fallout something that people will still want to play needs to be left. This is shaking things up, not changing the series into something unrecognisable and unwanted.
Example: All Fall Down
The band has split up - and the Siren has Adam and wants Billie to steal the Stone of Fire in exchange for his life - and Josh made a pass at Zora - and the Watchers have sent a group of agents to try and clean up this mess - and -