It used to be that when a designer showed an item in a particular season and you did not get a chance to buy it, you were out of luck. And if you really wanted it, a hunt ensued. You would call stores in other cities. You would pray that the item would pop-up on Ebay or Yoox in your size, or at your local consignment store. Or you would have to accept defeat.
But as designers have become savvier at business, they realized that if the customer wants something, they should give it to them, again and again. Perhaps they learned the lesson from watching luxury houses fling it-bags season after season with great commercial success. If it could be done with bags, why not with clothes?