The length of time allowed by the label "use-by" date, freeze/thaw, etc, should be considered. I generally don't go longer than 12 hours, unless I just brought it home from the store in the last day or so, and have some extra days left on the "ticking clock". 8 hours or more will get the salts from the rub working on the surface pretty well for adhering the rub and aiding in forming the beginnings of your bark (if that's your method). Most of the time I don't wrap and rest in the fridge at all, unless I'm trying to prep ahead to save time for a middle of the night start-up on a smoke, but the method does have it's merits.
Eric