In general I prefer separate threads, but I make an exception for <blank>.
Shows which have less interest here and therefore can only realistically sustain a season long thread…
Also this. Which I only posted to back up my vote.
I prefer separate threads. If I see a single thread for a show I’m unfamiliar with, it makes me think it’s a crappy show.
I really don’t have a problem with one long thread, as long at the different episodes are clearly delineated. I liked how the Doctor Who threads went, except for that one thing.
An easy way to handle that would be to use the post title to indicate that you are the first post about the new episode. and if the show is older, then everything up until the episode in that title shoul always be spoilered, ala Olives’s Buffy thread.