“The United States is a graveyard of European retailers,” says José Luis Nueno, a professor of marketing at I.E.S.E. Business School in Madrid. “Everyone who has gone there has struggled. Laura Ashley has shut down and even Benetton is declining. The U.S. is really complex because it’s about putting stores in shopping malls in the middle of nowhere. Fashionistas live on the East and West coasts. Then everyone else dresses in the Gap and Walmart and T. J. Maxx. If you really wanted to cover the U.S., you would have to open 300 stores, and they would have to focus all their energy to make it work.”

There’s also the delicate matter of sizing.

“Would you expand in the United States?” Fraiman asks. “Zara to me is a European store for European style; it’s very fashion forward. And what is the problem in America? They don’t fit in the clothes. So why do it? Having to make larger sizes makes production so much more complex.”

Expanding in China, however, will make production more complex and also require heavy investment. The company plans to open more than 400 stores there this year. “Even opening three stores a week is very aggressive,” Fraiman says. “Their factories in La Coruña have a finite capacity to respond quickly. You open more and more stores, and you don’t have flexibility of the last-minute response. Once they have a big thrust in China, then what happens is that they will have to take the whole model” — the processing of customer reactions, the quick-turnaround design teams, the logistics platform — “and replicate it in China.” But the bigger Inditex gets, he says, the more it will lose control over quality and efficiency.

Still, Asia remains central to Inditex’s plans, and the prospect of more than a billion Chinese consuming clothes at the fast-fashion clip worries some critics of the industry model. According to Elizabeth Cline, the author of “Overdressed: The Shockingly High Cost of Cheap Fashion,” Americans buy 20 billion garments a year, an average of 64 garments a person. When the Chinese are consuming at the same rate, that’s more than 80 billion garments a year. Golsorkhi says that fast fashion hasn’t changed the amount of labor needed to make clothes or the waste created by their production. Your new fluorescent miniskirt might only cost $40, but Bangladeshi workers still work for low pay in poor conditions to make it. Inditex says it works with unions and other organizations “to have the most respectful supply chain” and audits all of its partners every year, but like most major fashion companies that outsource the manufacturing of their clothes, it has received its share of complaints about factory conditions.

“The reality is: a T-shirt is a T-shirt is a T-shirt,” Golsorkhi says. “It costs the planet the same thing whether you have paid £200 for it or £1 for it. It does the same amount of damage. A T-shirt is equivalent to 700 gallons of water, gallons of chemical waste, so much human labor. But it used to be that we could do with three T-shirts a year. Now we need 30. Sometimes it’s actually cheaper to throw away clothes than to wash them. That has got to be wrong.”

It also may not be good for business in the long run.

“Eventually, there aren’t going to be resources to sustain fast fashion, so to me it seems to be a very vulnerable business model,” says Alex McIntosh, the business and research manager at the London College of Fashion’s Center for Sustainable Fashion. “Production costs will also get more expensive, and they won’t be able to keep this up. Value-based companies don’t have margins to absorb that additional cost. And then they will need to convince customers to spend more for clothes again.”

At the end of my tour, I went to one of the Inditex factories. There were about 100 workers, I was told; huge machines do much of the work. Hundreds of bright red three-quarter-length coats were hanging throughout the building, almost ready to be shipped. A line of women stood at ironing boards, smoothing out the wool-blend, looking for defects and, the spokeswoman told me with emphasis, attaching security tags. Inditex had discovered that if that task was left to the employees in the stores, it would take an extra few intolerable hours to get that trendy red coat from Galicia into your closet.