Remi remembers when.
In the field
Remi is Rejoin’s hummingbird, and real hummingbirds keep a schedule. Researchers set out eight artificial flowers in the territories of wild rufous hummingbirds in the Canadian Rockies. Four flowers refilled 10 minutes after a bird emptied them. The other four took 20 minutes. The birds learned both timings and came back to each flower at about the time it refilled.1
In your store
Your customers have refill times too. For example, Liam gets through a bag of coffee in 18 days and Sofia in 45. Rejoin learns each customer’s timing from your order history and sends their reminder just before they run out.
Come back too early and the flower is still empty. Come back too late and another bird got there first. Reminders work the same way: too early gets ignored, too late can lose the sale.
Henderson, Hurly, Bateson & Healy (2006). Timing in free-living rufous hummingbirds, Selasphorus rufus. Current Biology 16(5): 512–515.