Retention windows that match how people return
Seven-day and thirty-day defaults hide products that are weekly tools. Pick windows from observed return patterns.
Copying a retention template from another product is a common way to misread your own. A weekly planning tool and a daily messaging app do not share the same healthy return shape.
Look at the distribution of gaps between sessions for active users. Choose windows that sit near those natural gaps, then keep them stable long enough to compare releases.
Changing the window every sprint makes every chart look like progress or decline. Lock the window; change the product.