User blog comment:Rappy 4187/Technical Update: September 7, 2015/@comment-3388044-20150909041557/@comment-1757994-20150909172747

My Watchlist preference is set for 7 days.. Things fall off my watch list after 24 hours, even if I specify days=7 in the URL. Changes that happened yesterday (after I first noticed the abbreviated list) are apparently too old today.