Blog - Lauren Pearl · Lauren Pearl
articleinsightWhy does AI suck at Excel?
24 April 2026Profit
Source excerpt
About Blog - Lauren PearlI've been playing around with using Copilot and Claude for building models in Excel, lately.As I've been playing*, I've noticed something:Using AI can really speed up some building.Some of my favorite prompts so far:"Can you make the model formatting prettier?""Can you review this whole model and tell me where there may be mistakes?""I want to use this model in a demo. Can you sanitize it of any identifying data?""I'd like this revenue forecast to be based on a marketing funnel. Can you build me a marketing sales funnel tab and use it to calculate new customers each month?"The power is incredible. I could save so much time!But there's a huge downside:I can't trust the output.Some examples of mistakes I've discovered (which doesn't include the ones I'm still unaware of):It sometimes uses insane formulas that are heavy, really hard to understand, and overbuilt. Eg. a million nested…
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Apollo layer
What a founder can learn
Founder takeaway
Treat AI in financial models as a fast but fallible assistant, not the final authority. Use it for drafting, formatting, sanitizing data, and identifying possible errors—but require simple formulas, traceable assumptions, and human verification before relying on the output.
Why it matters
Spreadsheet mistakes can quietly distort forecasts and operating decisions. A controlled workflow preserves AI’s time savings without turning opaque or incorrect formulas into business risk.