The quest by big retail chains in the US to offer fast fashion -- on-trend apparel delivered before it goes out of style -- remains a challenge. The stakes are high to make fast fashion work. A rapidly changing assortment of trendy clothes helps drive customers into stores, and potentially stave off the encroachment of online retailers.

In the last couple of years, people started realizing they have to speed up. And one of the reasons is the consumer has really sped up. As consumers jump from one trend (and brand) to the next faster than ever, US retailers are collectively being forced to pivot away from the traditional model, which values low costs above all else. The methods they’ve adopted vary widely.

For now, few US retailers can match the fast-fashion prowess of European competitors such as Inditex and H&M. These companies pioneered the model by taking flexibility to the extreme, via airlifted merchandise, small order sizes and an accelerated design process.

A transition to fast fashion is also complicated as most US retailers depend on suppliers, while a company like Zara is vertically integrated -- allowing more control from start to finish. That means, for US apparel vendors, the acceleration has to occur across multiple companies.