They're the ones you can listen from start to beginning in order every time. The ones you never get bored of and if you do, you have a need to listen to them again pretty soon.
The chance of me grabbing an LP off the shelf and listening to 6 Underground by the Sneaker Pimps from their Becoming X album is exactly is zero. It's a banger yes, but the rest of the album is decidedly not worthy of the ceremony.
I also think listening to one side of an LP and then switching to a different one isn't that much more work than flipping it over, so it's OK if only one side is flawless. I will listen to Arlo Guthrie's "Alice's Restaurant" anytime, even though the songs on the other side are not as iconic/necessary.
Finally, I think you may not know ahead of time which albums become beloved and worthy of the ceremony upon repeated listening. I bought my partner "songs" by Adrianne Lenker (of Big Thief) because she loved "anything" from that album, and now that double album is one of our favorite albums that we're currently wearing out. I think it's worth taking a risk sometimes, and if you don't love it, you could sell it to a used record shop for someone else to love.
This is what I like about it really. It's quite a deliberate focussed thing. For most of my music listening when I just want noise in the background I stream it because it doesn't matter. But sometimes when you just want to sit down and enjoy something special, the ceremony seems to add something.