From the article:
The same-store sales figure is fickle at best. For instance, the month
of May included an additional Friday, rather than a Tuesday. Jefferies
analyst Andy Barish notes the former is a busier time. “That 2.4% growth
in the US is more like 1.4% when you compare apples to apples and
account for trade day shifts,” he adds.
“The real nirvana for this company is if they can sell premium products but also drive traffic and value. Those two things run incongruously – when you promote value, it’s hard to drive a premium product,” Barish adds.
The Problem With McDonald's' New Premium Menu Options - Forbes