One problem watch for with your repeat purchases is the average order value (AOV) dropping on repeat purchases.
For the most part your AOV should be holding steady or increasing as specific customers buy again and again. If it's dropping, that's a sign of a potential problem that you'll want to look into.
This is also a symptom of heavy discounts to repeat customers, some who might have bought at the regular price.
There are exceptions. If you sell something durable that needs replenishment, you'll see a higher than normal first order (e.g. buying equipment) and then smaller repeat orders (e.g. buying refills). Even then though you should see AOV steady or trend upwards in the replenishment orders.
If you need help checking the AOV on repeat orders, that's included in the Customer Purchase Latency report in Repeat Customer Insights.
Eric Davis
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.