One that I find useful is to graph how many loyal customers you have over-time. This lets you easily see trends and loyalty problems.
In a healthy store that's growing, you should see both increasing over-time. They might not grow at the same rate but they should be consistently growing.
If they flatten, that's a sign that you're losing loyal customers that aren't getting replaced by new customers. This should be a wake-up call to get to work on your loyalty systems.
If they go down, you're well into the problem and need to do whatever you can to keep customers around. Hopefully you'll notice any flattening trends early and prevent drops.
The new Who Are Loyal focus inside Repeat Customer Insights will automatically graph how many VIPs and Above Average customers you have. It uses the historic Customer Grid data that's collected every month so merchants who've had the app for awhile will have a lot more historic metrics showing up.
But even if you just signed up recently (or plan on signing up in a minute), the sooner you start to collect this data the better.
Use cohorts to find out who the best customers are in your Shopify store
Repeat Customer Insights will automatically group your customers into cohorts based on when they first purchased. This will let you see how the date customers bought would impact their behavior.