Good point. I've seen miracles occur simply by refactoring an Excel workbook such that the inputs, outputs, and calculations to map the inputs to the outputs were all delineated into their own clearly-formatted bounded context. And also, when you do drop into vba code, simply organizing the code so that interactions with the sheet are easier to understand, and isolated -- and focusing on "seriality" (no feedback loops, minimize code triggered by events) can transmogrify vba code from the Bogeyman into a friendly neighbor.