Let’s say you want to call your mum ideally once a week, but not more often than that. You might want a reminder that reminds you each week, but that will automatically leave you alone for a week once you’ve called and caught up with her . So ideally: a weekly reminder (let’s say Thursday this week). But if you don’t call until Saturday, then it will automatically remind you a week on Saturday when you click complete. This way it will always remind you *one week after your last call*, rather than always on a Thursday.