The success of online advertising campaigns is often measured solely by lifetime value (LTV) margin, which can lead to a ceiling on growth. However, the rate at which a campaign returns capital, also known as the payback period, is a critical factor in determining the best campaign and its potential for long-term growth. Focusing solely on LTV margin can result in overlooking the importance of payback periods, potentially leading to missed opportunities and underperformance. By considering both unit economics and payback periods, marketers can make more informed decisions about where to allocate limited capital and reinvest cash back into customer acquisition, ultimately driving business growth and profitability.