1. What is the problem or goal the end user is trying to solve or accomplish?
To make comparing YoY easier, and it would be easier to read the calendar heatmap from left to right then down. This is problematic when you compare several years of data. Having an easier presentation of days YoY will make it possible to compare “fiscal Day of Week” or “fiscal Day Of Year” compared to the data from previous years.
2. How are they solving it currently?
Currently, you can still use the calendar heatmap, but it's a suboptimal experience because the chart is only scrolls to the right.
3. What is the recommended solution by the Customer?
Making the years stackable up and down would make it easier to compare several years of data. This would require a third "domain" (superdomain) to be added that decides the vertical stacking timegrain of the heatmap.