Why do my complex models still break when the simple ones work?
You can build the spreadsheet. The formulas are right. Yet on the deals that matter most, something breaks. You cannot trace it to one broken cell. That is because the model is not the problem. Somewhere inside it sits a number you never questioned. A growth rate. A multiple. A timeline someone handed you in a meeting. You built on it as if it were solid ground. It was not. It was a guess wearing a suit. The habit you lack is not modeling. It is interrogation. Before you let any number drive the outcome, ask it to prove itself. Do that, and the complex deals stop breaking you.
The model is not breaking. An assumption inside it is doing unexamined work, and you are treating a guess as ground. Choose, before you build, to name each assumption in plain words and test it alone. That habit — not a better formula — is what will hold the complex deals together.
What changes unlock by starting
- You catch weak assumptions before they reach the final number.
- You can state, in one sentence, what has to be true for the deal to work.
- Complex deals stop surprising you at the end.
- You build a habit of questioning inputs that holds up under pressure.