Just to echo most of what has been posted here.
Most made to order/ custom juice is shipped right after it is mixed. In most cases it needs "steeping". Off the shelf juices like DeKang typically don't. They have been mixed a while when you get them.
Good analogy is spaghetti. Always better the second day right? The spices have had more time to blend and it tastes better. Same with juices only the time frame is a little longer.
Most believe some breathing (cap off) time is required or at least helpful. Amount of time varies but I just take them off a couple of hours to start the oxidation. Some say 24 hours.
Shaking is pretty much a must for most flavors. Vigourously for a short period once or twice a day for the first few days can do it. Then let them sit. Time varies to taste but most juices are okay after a week. Tobs, coffees and some other may take longer.
Store in a cool dark place. Not cold as the refer will peserve the juice and slow the steeping.
A lot of juices hit their sweet spot about a month in but it is really to your taste. Not sure about the ultra sonic cleaners but they are building a strong following with some wise and experienced folks.
I am still a bit of an inexperienced newbie but I have studied at "Ms. EleanorR's" school of steeping
