It's really baffling how frequently stuff I've already watched shows up on there. Netflix's whole design revolves around obfuscating the size of their catalogue as much as they possibly can. It's why they rotate categories and thumbnails as much as they do. But when I see like 5-10 things on my recommendations that are things I clearly already watched and rated on Netflix or it's stuff that doesn't have a great recommendation percentage, it just makes me think there must not be enough on Netflix for them to recommend to me that I will like.