Spreadsheets are apprentices. Teach them one clean move and they’ll repeat it perfectly a thousand times. The temptation is to improvise down the column… little tweaks in row 7, a “fix” in row 23. That’s how you lose the plot. Instead, make one formula that tells the truth, copy it through, and let the machine be the machine. If a special case appears, solve it by improving the move (not by sneaking in edits). Lock references when needed, label inputs plainly, and let formatting earn its keep by clarifying, not decorating. The goal isn’t a “finished” spreadsheet; it’s a dependable one. When the apprentice learns the move, you get your brain back for thinking.
