On a track that earned its slot back

There's a track that I've taken off the sleep playlist twice and put back three times. It's a long ambient piece by an artist who doesn't otherwise appear on the playlist. The first round of testing said yes; six months later I felt it didn't fit; a year later I missed it; six months after that it left again. It's currently on.

What I learned from this track is that the room changes around the music as much as the music settles into the room. The sleep playlist this winter is not the same playlist it was last winter, even though most of the tracks are the same. The room has a temperature, and that temperature shifts. A track that doesn't fit at minus two degrees might fit at plus three, and the test only works in the room as it currently is.

This is part of why the rooms are not a sealed product. They drift. Tracks come back in. Tracks that were inarguably right last year fall away. The drift isn't because I changed my mind; it's because the room did. The listener who's been with the playlist for two years has heard a substantially different room than the one they started with, even though it has the same name.

The track in question, for what it's worth, is the kind of music I would have rejected on principle five years ago. Tastes change in slow loops. The room I'm building now is partly the same as the one I was building then, and partly someone else's room, and I won't know which is which for another few years.