Apps don't actually have any control over when they get woken up for background fetch (you can set a minimum interval, but it's very much a minimum), and the mo

Apps don't actually have any control over when they get woken up for background fetch (you can set a minimum interval, but it's very much a minimum), and the more work you do when you get woken up the less often it happens. In practice for occasionally used apps it seems to happen once a day, and while you're on wifi and charging if possible.