Trust your gut instinct over spreadsheets. There are too many variables in the real world that you simply can't put into a spreadsheet. Spreadsheets spit out results from your inexact assumptions and give you a false sense of security. In most cases your heart and gut are still your best guide.
All species capable of grasping this fact manage better in the struggle for existence than those which rely upon their own strength alone: the wolf which hunts in a pack has a greater chance of survival than the lion which hunts alone.
