I purchased an RY-4. When I opened it fresh from the mailbox and vaped it, it had a terrible chemical, artificial taste. I thought, "that was a wast of money."
I had read about steeping here in the forum, so I just set it aside. I keep mine in a box, out of light. Some recommend a dark, cool place. After 5 days, the flavor had improved quite a bit. A week and a half after I received it, it became my favorite, go to vape. An amazing change in flavor.
I usually test flavors when I first received them. If they're not up to par, I just let them sit for a week or so. Perhaps some juices need time for the flavors to fully meld, and I suspect other flavors will never tickle my tastes buds, no matter how long they sit.