This flyer has been circulated by anew cafe near my office. I think they are making a mistake with their pitch as the different discounts are not time based or targeting different categories. If I was them I’d offer 50% for use within 48 hours, 30% for use within 7 days and 15% for use within 30 days. This approach would separate the discounts and offer relevance for the different percentages. As it is without any difference it looks a bit odd to me.