1. The Pareto Principle _ Using spreadsheet tracking, you can easily apply the Pareto principle in deciding which of your income sources and expense channels(i.e. products and services sales) to focus on in order to maximize profits. Considering that you are most likely to use the same marketing/sales resources to serve your customers, it only follows that if you focus on your biggest margin selling products/services, you will get increased profits at more or less the same cost.
The savings _ from using your "in house" expertise _ in terms of money and man_hours alone, will quickly justify the investment you make in "developing the needed skills" _ especially, when you compare what you spend with the cost of purchasing a commercial software application _ or even engaging the services of an Excel VB developer.
2. Sourcing Capital _ For Expansion or Startup. You can make it easier for banks and prospective investors to back you financially and/or take the decision to buy into your business. Those already running their businesses will know that banks like to see detailed business records that show in real terms all aspects of a business' performance. Without detailed and comprehensive spreadsheet tracking, it might be difficult to show this. Agreed there are software applications that capture most of these. However, sometimes, you want to highlight certain scenarios or trends in a way that an off_the_shelf application cannot accommodate due to the uniqueness of your need. It is in this regard that the use of spreadsheet tracking becomes relevant.
The 80ᚼ Pareto principle is based on Pareto's theory that 80% of the results one gets in a particular endeavour will be mainly due to 20% of areas to which one has applied efforts. In business this principle has been found to be true. Your data, properly converted into appropriate performance indicators, will show you where your largest margins come from. You can then channel more time and effort in that direction.