Although intentional circular references can be useful, using this feature has some potential problems. Perhaps the best advice is to use this feature with caution, and make sure you understand how it works.
To take advantage of an intentional circular reference, you must have the Enable Iterative Calculation setting in effect. When that setting is in effect, Excel does not warn you of circular references. Therefore, you run the risk of creating an accidental circular reference without even knowing about it.
The number of iterations specified in the Maximum iteration field applies to all formulas in the workbook, not just those that use circular references. If your workbook contains many complex formulas, these additional iterations can slow things down considerably. Therefore, when you use intentional circular references, keep your worksheets very simple and close all workbooks that you aren't using.
You may need to distribute a workbook that uses intentional circular references to other users. If Excel's Iteration setting is not active when you open the workbook, Excel displays the circular reference error message, which probably confuses all but the most sophisticated users.