Final answer:
Performance Planner is used monthly to forecast ad performance and optimize budget allocation, similar to an economist predicting and comparing stock market trends. It facilitates agile, data-driven decisions for ad strategy adjustments, improving ROI.
Step-by-step explanation:
The Performance Planner should be used every month primarily to forecast ad performance and budget allocation. This tool helps in planning ad spend more effectively by simulating what could happen across different bid and budget levels. This monthly review allows marketers to stay agile, making data-driven decisions to optimize ad spend based on changing market conditions, competitors' actions, or performance trends. Similar to an economist deriving a model to predict stock market outcomes, and comparing expected points on a stock market index with actual points to measure accuracy, Performance Planner compares expected performance with actual performance of ads. Regular monthly usage enables adjustment and refinement of marketing strategies to improve return on investment (ROI) and achieve business goals.