This year's Black Friday and Cyber Monday were bigger than ever. But the numbers could be concealing an underlying trend away from those key dates in the retail calendar.

Deep inside a sprawling glass-and-cement edifice the size of an airplane hangar in the Spanish town of Arteixo, 10 designers swarm around a model dressed in cropped gray trousers and a double-breasted navy blazer. Sweaters, shirts and suits are spread out on the white-tile floor, while seamstresses in white labcoats stitch prototypes nearby. "It's classic, but it's new at the same time," says a woman from China. "I'm not sure about the bold patterns," counters a British woman, dressed in white sneakers and a flowing skirt. Others nod their assent or express doubt.

With the middle of the holiday season approaching and shoppers eager to take advantage of early promotions from retailers, more than half of consumers have started making dents in their holiday gift lists, according to the annual mid-season survey released by the National Retail Federation and Prosper Insights & Analytics.

It can be hard to ignore the lure of Forever 21, where fall jackets go for $18 and a halter dress can be had for $9. But U.S. Labor Department investigators contend that those deals are costly for people like Pedro Montiel, who said he makes $4.50 an hour putting the labels and other finishing touches on blouses for one of the retailer's suppliers.

For retailers and distribution centers, the traditional method for coping with the chaos of the Christmas buying season has been to throw more bodies at the problem. But what if robots could do a better job of handling the surge of activity?