Retailers never know and most items are bought months in advance, then if you have a popular item can be out of stock with ad printed months in advance, or will have an item that flops and then dosen't sell, or trendy item or person falls in disfavor with public and can't give away.
Retailers just never know, mostly speculation.
Have never figured out the aggressive shopper, chances are the world won't stop spinning if little one dosen't get what whey want.