https://phys.org/news/2019-02-apple-retail-exec-iphone-sales.html

During her 30 years at Apple, O'Brien also helped gauge product demand. That issue has become a problem now that customers are holding onto their current iPhones longer instead of buying the latest models. It's one reason Apple posted disappointing iPhone sales during the past holiday shopping season.

Although Apple sells iPhones and other products such as the iPad and Mac computer through a wide variety of merchants, its own elegantly designed stores have become a pivotal outlet, especially during the first few weeks after a new device hits the market.