It's a misconception that work in Excel can't be documented or reviewed. We have the seed data he uses and the resulting Excel files (with the formulas he used still in them). This is the equivalent to version control for programming. The results are also reviewed against 1-2 appropriate sources (invoices, historical data, multiple other reports built by IT) for accuracy. To your very legitimate point that he's the only one doing this work, if he left, long-term we would probably need 3-4 people to take over his work. Short-term, the company would probably need to put together a triage team of 5-6 people to take over his existing processes. We actually moved some of the hedging to a different team last year and we had to hire two business analysts and implement a industry-specific system to do so.