Your line chart shows monthly revenue, but people want to see the trend smoothed over 3, 6, or 12 months next to the raw actuals. The usual fix is a separate DAX measure for every KPI and every window size — and suddenly you're maintaining dozens of near-identical measures.

A calculation group does it once for every measure in the model. Drop it on a slicer, pick "Rolling Avg 3M", and any measure on the chart smooths instantly — and if you already have the Time Intelligence group, these items merge straight into it so it's all one slicer.

The fiddly part is the start of a series: a 3-month average has nothing to average over in month one or two, and without an explicit guard it quietly divides by the wrong number. This skill writes the correct pattern, handles the merge, and produces valid TMDL in a single command — run it with /rolling-averages-kit.