1. Enterprise ..... as soon as they read the scripts and saw that this was not a pre-Kirk show, but an attempt to go backward and forward at the same time.
2. Stargate SG-1 at the conclusion of season 8. Threads was a good place to stop
3. The Twighlight Zone (the new version). You can't go back. They should not have tried
4. Touched by an Angel. After season one. One was enough....
5. Star Trek: TNG ; they should have cancelled Wesley Crusher day one and removed all the poles up everybody's backside on day 2.