When do you personally think a tv series should have finished?

[Soubriquet]

The last season of Once Upon A Time should not have happened.

It ended with a good ending in series 6, and then tried to do an entire new series with the same story line. Bad failure.

Glee. Although there are some good episodes when the original cast left for college, it should have finished after they won nationals and graduated high school.

Handmaids tale. I think it should have finished after series one.

Being Human, should have ended after season 2. It could never be the same without Mitchel, and I was also disappointed by Nina's between seasons exit.
Obviously Heroes should have been one and done. I think even without the writers strike season 2 wouldn't have been a patch on the original. With it there was no chance.

I loved the Tudors series 1
I liked series 2
Series 3 was rubbish
I didn't finish series 4