When I worked in consumer products, virtually every brand had its own regression analysis showing the various options of sticker price, promotional price delivered by a temporary price cut vs. a coupon, other “special deals” and the impact on volume and profitability.
There was an entire category of products where the single most profitable option was “Buy two get one free”. Even when just lowering the price- permanently- meant that the product’s unit price was lower. Sometimes significantly lower. That just didn’t move the needle for a huge chunk of consumers. They’d rather pay more but gaze fondly at their “free” tube of toothpaste or gallon of floor cleaner.
Of course there was always the newbie employee who explained that the “buy two get one” crowd were clearly innumerate. And if someone actually showed them the unit price they’d retreat. Nope. Both the sales data and the market research findings showed that consumers didn’t care. The entire point was getting a deal– not paying less.