This is sort of related to my question on bourbon release intervals.
Say a distiller makes several older products (12 yrs and older). Do they designate which barrels will provide which age bourbon? As they age, do they sometimes determine that what had originally been intended to be 12yo product, would now do better as a 15yo, for example? In other words, are barrels commonly shifted forward (or backward) in time, and if so, does that wreak havoc with intended supply inventories?
I'm certain that a couple of distillery tours would answer this, but I haven't yet had the opportunity.