Manny Karyampudi pointed out to me a problem with some of my book samples, that turned out to indicate a regression in the behavior of AlarmManager on Android 5.1. (book sample apps are useful canaries in the Android coal mine…) Up through Android 5.0, the repeat interval for setRepeating() and setInexactRepeating() could be fairly low. Some of my book samples, like this one, go as low as 5000ms,