The RFM analysis that I use with Repeat Customer Insights gives each customer three scores from 5-to-1 based on how the customer ranks.
Customers who have all 5's are your very best customers, what I call the VIPs. These are customers who have ordered recently, have placed the most orders, and have spent the most over their lifetime.
When you're wanting to know who are your most loyal customers, these are them.
If they continue their buying behavior by placing more orders, they stay loyal.
If their behavior shifts any one of those factors and their score drops, that's a sign they are losing their loyalty. This balancing is why RFM is a great measurement of customer behavior. It works with small stores, large stores, and auto-adapts to all changes in your store over-time.
These VIPs are reported on in the new Who Are Loyal focus page in my app along with other loyal segments. Even if you don't want to do much, targeting them with your loyalty campaigns and programs will be worthwhile.
Market to your customer's timing
Figure out how long customers wait in-between purchases and you have a key component for your marketing timing. This is the basis of the Average Latency metric and Order Sequence Report in Repeat Customer Insights.