Excel spreadsheets tend to quickly become very difficult to understand for people that are not the author. Formulas can be quite lenghty, and lack some comments explaning their logic and purpose.

Power-user includes a simple feature that will help you keep your formulas simple, by removing redundancies such as referring to "Sheet1!A1" instead of simply "A1" when you are already in "Sheet1".

With simpler formulas, it will be easier to share your files with other people and have them understand or audit your formulas.