Optimal Answers will assist you in performing a Savings Analysis. The analysis is typically a comparison between your current plan and a plan developed by the Optimal application. Typically a 5-10% savings.
https://www.forbes.com/sites/billconerly/2013/04/25/every-spreadsheet-has-an-error-7-lessons-motivated-by-reinhart-and-rogoff/?sh=25df79333f2b