You may know this but also stating this for others as this may not be so obvious.
If you have access to the Discourse AI bot which can be found in the upper right corner
then using Forum Helper persona you can also try out different instructions that could be used with the custom instructions of the Periodic report using AI. In other words you can use Forum Helper to quickly prototype the report.
As one who was privileged enough to assist with feedback during development I can tell you that the custom instructions are important for getting the desired results. In the example given above I can clearly see that Sam added this for your variation of a report based on your initial request
HTH