Here's what happens to me occasionally when doing a "fetch quest" in a video game: I can't find the last item needed to complete the quest. I got all the others, but the last one is hidden away somewhere and I can't move the game forward a single inch until I find that very last one.
So I ask myself "What rooms haven't I been in?", "What doors haven't I opened?", "What box/crate/container haven't I looked in?" etc.
... and off I go exhaustively searching for that very. last. one.
I would hate to have to go searching through hundreds of mundane "template rooms" & closets that contain nothing of interest.