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.
It breaks my heart to see these young really talented bands getting chewed up into the system. I remember a time if you'd signed to a major label it was such a sell out! But now... unless you've signed to a big label you're a failure now.