Open a display ad from a credit card company, a financial newspaper, a magazine subscription service, and a smart-home gadget startup, and you’ll notice something odd: they’re all speaking the same language. Not the same product, not the same audience, not even the same price point — but the same four words, somewhere in the headline: limited time only. A creative-text search across Adbeat’s index for the phrase “limited time” turns up this pattern at scale. Capital One uses...