The reason to collect and analyze metrics is to help make a decision.
No decision, no point in collecting metrics.
Sometimes you'll want to collect metrics ahead of time though. That way when you're ready to make a decision, you have enough historical data to support you.
That's why every website installs Google Analytics or a similar traffic tracker. In the early days you don't have many options for decision-making but 5 years down the line, having 5 years of data accumulated becomes valuable.
That's how Repeat Customer Insights is able to create historic reports for your store even if you just installed today. Shopify saves a bunch of order, customer, and product data just as part of its normal operations. So when Repeat Customer Insights gets installed it can go back through all of that data to analyze it and pull out recommendations for you.
All that historic data ends helping the analysis and supporting the decision making that you make in the present.
Because that's the point of it all. The decisions you're making now and in the future need a complete view.
Promote products that create your best customers
When it's time to run a promotion, how do you pick the products to feature? Best sellers are okay but wouldn't it better to promote the products that crate the best customers? Repeat Customer Insights will analyze your product and buyer behavior to show which products and variants lead to the highest quality customers.