This weekend I started cleaning up the garden beds for winter.
A big job is adding compost to the soil so over winter and into spring it can feed the soil.
The problem is that I didn't create enough compost this year. The first batch I used elsewhere so I'm missing 1/3rd of what I need. That means have to go light with what I have left which means weaker growth next year.
That's a long time between cause and effect but that's how natural systems work. It can take a year (or years) to see how a decision plays out.
Customer behavior doesn't take as long but it usually works on scales that are longer than most reporting picks up. Making a decision now (e.g. limiting offers to VIPs) might not show up until next year (e.g. as VIPs go elsewhere for holiday shopping). That won't show up in any monthly sales report.
This requires thinking about and measuring impacts over multiple years. The default timescale in Repeat Customer Insights is your full store's lifespan for that reason. A quarterly or even an annual view would limit what you can learn from your data.
When it comes time to make decisions around customers, give them the time needed to think through the long-term impacts. Not just what will change this month.