We are speaking about how to manage a BFCM sale and the data definitely says that coupon codes are a significantly worse alternative to a site-wide markdown. It

We are speaking about how to manage a BFCM sale and the data definitely says that coupon codes are a significantly worse alternative to a site-wide markdown. It is all about friction reduction. Asking users to type in a coupon code adds a step that doesn't need to be there. This doesn't mean that coupon codes are never useful, but in this particular case we would recommend making the experience as seamless as possible.