Your business cycles are important to understand.
A down month might be from your typical cycle and not have anything to do with what you did (or didn't do) this month.
This point was driven home to me once by a Shopify store complaining about a low month. With one glance at their sales trends it was clear they were at their natural low-point in their cycle. Wait a month or two and they'd be hitting their peak.
The other benefit of knowing your own cycles is that you can better time marketing campaigns. You can shore up weak periods or boost the busy season on your schedule, not the cycle's.
Eric Davis
P.S. Beyond business cycles, you'll want to make sure you're improving year-over-year. Repeat Customer Insights can track and measure this for you as part of it's Insights system.
Start noticing seasonal spikes in customer behavior
Cohort reports let you detect seasonal spikes as well as long-term retention cycles. Repeat Customer Insights can automatically create cohorts for your Shopify store, going back to your very first order.