A music store wants to understand the percentage of repeat customers to run a customized campaign. Which insight would be most useful to review to build a strategy around?

The correct answer is Purchase frequency insights, as this metric specifically provides valuable information about how often customers return to make purchases. By analyzing purchase frequency, the music store can gauge the percentage of repeat customers, enabling them to identify loyal patrons and understand their buying behaviors. This insight is crucial for developing a customized campaign that targets these repeat customers effectively, potentially increasing engagement and sales by tailoring offers or promotions to encourage further purchases. In contrast, demographic and timing insights may offer useful information but do not directly address the repeat customer aspect as effectively as purchase frequency does.