I mostly agree with Yooper except 1 thing, if you carb up a 65 deg. F beer at 25 psi or whatever, chill it down to 40 deg. F overnight, then drink some of it the next day, it will be appropriately carbed. If you leave it under 25 psi for a week and come back to it, it will almost certainly be overcarbed. I'd say if you are going to store for a long time (days-weeks), you probably want to use the pressure at the storage temperature.