A huge variety of behavior can get lumped in with customer behavior. Some behavior is positive, some negative, and some neutral.
Loyalty and retention programs at their core are tying to encourage a limited set of positive behavior (e.g. buying, social sharing). There's more behavior that you might want to encourage or discourage in your store though.
It's a good practice to sit down and list what behavior an ideal customer would have. Consider all types, don't limit yourself to just positive behavior.
If you describe exactly how an ideal customer would interact with your store, it can become easier to build systems to support or discourage that behavior. Those systems will make running the store easier as customers are guided closer to becoming your ideal customer.
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.