90% as a non-configurable “watched” amount is wrong. Many of my media is 4 hours long. There’s still nearly 1/2 an hour of content when I get to 90%. You should let the user configure what percentage (or better yet, chose a percentage or a specific time like 3 minutes) before a show/movie is marked as watched and you destroy their location.
There’s already an existing feature suggestion discussing that option. Please comment/vote in that thread in order to avoid distracting or cannibalizing votes.