Right now, if a new user joins and adds a bunch of shows with numerous seasons already in the past, they have to go to each page for each show and mark everything watched. It would be a lot more convenient if the Watchlist also had a "watched everything to this point" next to episodes, as it already shows 2-3 of the most recent and chances are a new user has watched all but the most recent episode.
I understand it makes the UI a bit cluttered in that area, but I'm sure there's some way to do it cleanly.