Chart ALL rows of a report
Currently when you create a report in Workbooks you are shown the first n rows of data, where n is the value set in your 'Lists' preference. If you chart the report either for a standalone chart or for inclusion in a dashboard then you will ONLY see n values in your report.
If you report has more than the default value of 'Lists' you will NOT see the data on your chart from the additional rows. So yes you can alter your preference but if the chart is redrawn by another user with a different preference value, or the dashboard is viewed by another user with a different value, they don't see all the values.
Workbooks should either chart all the returned rows, or the number of rows specified by the chart creator or it should flag to chart viewers that not all the data is displayed (so they can look at the underlying report).