RE: The Good Place. The series finale just aired and it really was a good show. Schur is a good producer and the writing was solid. I also like it was designed for 4 seasons and they stuck to that. If more shows were like that, we would have better quality shows and not crap like The Walking Dead.
RE: Lost. It's still one of my favorite shows. After the writer's strike, it felt like they lost momentum to explain things and there's quite a few things that got forgotten. I'm actually rewatching it again now. The character development is still some of the best on TV IMO. The ending didn't bother me, I actually kind of liked the concept.
I stop watching typically when they start extending the show and it turns into something else. Stories should end when they naturally end, otherwise the characters become caricatures of what they once were and the plot stops making sense