As I harvest veggies from the garden I weigh and keep track of them.
It takes some extra work but the benefits are worth it. Measuring lets me use that data to decide what to keep growing, what to grow again, and what to ignore.
For example, so far this year I've planted two different lettuce mixes. Our own mix from last year's saved seed has produced over three pounds from nine plants. A commercial mix has produced about half a pound from 18 plants.
The season's not over so that second mix might still catch up, but it's clear that our mix is highly productive.
If I didn't keep track, I might favor the commercial mix. It's prettier and more visible out our windows, but it's producing far less.
When you're looking at customer loyalty you might run into similar problems if you're not measuring the right data. You might think a customer is loyal but it could be because they are more visible to you (e.g. they live in a familiar city, have a name you recognize, or you talked with them once).
Actually measuring your customers and their behavior will reveal much more and ignore those familiarity biases. Repeat Customer Insights uses a few different models to measure your customers for you so you can find who your most loyal customers are.
Learn which products lead to the customers who spend the most
You can use the First Product Analysis in Repeat Customer Insights to see which products lead to the customers who spend the most. Going beyond best sellers, it looks at the long-term purchasing behavior of your customers.