For a Scottish made whisky to be called “Scotch” it has to age in oak casks for at least three years. This allows the whisky to interact with the casks and draw flavours, as well as colour, out of the wood. The higher quality of cask and longer storage time, the more flavour it can pick up.
Because Ballantine’s has been making whisky for so long, they have some of the world’s most impressive stocks of aged scotch, meaning they can have blends aged for over thirty or forty years.
Once bottled, the maturation stops. So there’s no point keeping it in a wine cellar for years and years, it’s there to be had and enjoyed.