Typically we see clients wanting to plot multiple charts in their Opportunities report and the sorting can be problematic for them. In the following screen grab we show two charts from the one report.
Chart 1: column chart showing the total value by sales stage sorted 1-5 where 1 is new and 5 is nearly closed.
Chart 2: area chart showing the total value of sales by expected close month where months increment from this month onwards.
As you will see, if the report is sorted by Sales stage so that the first chart plots logically from 1 to 5, the area chart shows random months. If you sort by months ASC then the sales stage is random (e.g. 2, 1, 4, 5, 3 etc. )
Adding a chart sort order would solve this issue.