They do give them ample time to sell...they send the pieces (bags, ready to wear) around from store to store for a couple years for those who want them and may happen to call the 800 number looking for a piece. Then when they've been sent around to a majority of the stores, they offer them to the SAs for 80% off. THEN if they don't sell, they get burned.
But do know that the vast majority of pieces get sold before they get sent to the incinerator.
But do know that the vast majority of pieces get sold before they get sent to the incinerator.