Jeff Johnson points out that Apple’s first fiscal quarter of 2017 was an extra week long:
Most Apple fiscal quarters are 13 weeks long. Once in a while, however, they need a 14 week quarter. You might call it a “leap quarter”. There was a good explanation of this financial practice a few years ago in Slate. Apple’s Q1 2017 was a 14 week quarter, for the first time since Q1 2013.
He’s absolutely right that Apple was able to show greater per-quarter growth because this quarter was longer, and even a slow week would add enough to counting stats to push it above the year-over-year quarter, which was 13 weeks long.
We can unravel it more if we like: You can back out a huge settlement benefit that hit the first quarter of FY16, which makes Services look even better (but doesn’t change the overall net). You can start to calculate out the channel and supply constraints and get a better sense of demand. In other words, you can make the numbers tell the story you want to tell, with charts to match, and slice it nine different ways.
But, for better or for worse, the window we get into Apple’s finances is based on its financial statements—and that means the quarters as Apple defines it. This was a record quarter for Apple. But it’s also fair to point out that Apple’s definition gives it a one-time windfall, an extra week of sales that it won’t get again for another few years. And it’s a windfall that next year’s year-over-year holiday-quarter comparison will have to overcome in one fewer week.