Steeping is more important for juices that are mixed to order.
Some juices are great right away, others need some time to mature before they are good. I have noticed that fruit flavors tend to need to steep before they are good. Even some of my favorite juices that were great the day they arrived (FSUSA butterscotch is one example) got better over time. As I i got to the second half of my bottle of butterscotch, it has gotten even better. The vapor production is the same as day 1, but the flavor is richer, sweeter, more complex. I just bought a new 30ml bottle and you can see the difference. The juice in my original bottle is slightly darker and thicker than the bottle that just arrived.
Some need to steep longer than others. I know I am a big fan of instant gratification. I hate having to wait. When I get that bottle of juice, I want to use it the day it arrives. Sometimes USPS helps with the steeping wait. I had two orders that (by no fault of the vendor) took about a week or more to arrive. One came from NY then went to FL and spend 3 days in a sort facility there before coming to Atlanta. Then spent a day in the Atlanta sort before going out for delivery. The second made even less sense. From AZ, it was in ATL the next day. It spent 1 day sitting in ATL sort, then was sent to Memphis where it sat for 3 days before coming back to the same ATL sort facility and sat there for another day before being delivered. I stalk my juice orders online - watching every step they make on their way to me. It is so frustrating to see them being sent to unusual places rather than just coming directly to my house and PV. But, on the positive side, at least they arrive pre-steeped (assuming it isn't a flavor that requires a long steep).