Down to 200.
What I noticed was that I was using it as a bookmark and the function doesn't really fit the purpose really. There was like 200 videos that I had already seen. Then there was like 200 videos of music and about 100 videos of pure garbage that was unappealing based on the first minute or so.
It would be kinda cool if you could just 'tag' videos you want to watch later. Or could browse Watch Later videos based on genre. Of course none of this will ever happen since maximizing time watched is the thing.
I also have more respect for YouTubers who stuff besides the talking head genre (it's wider than vlogging) or narrating over clips or pictures.