And for a while, we did. Forecasts were living documents (in five tabs). We tracked cash burn on whiteboards. The budget was something I explained out loud more than I ever wrote down.

Eventually, I realized that if we were going to keep growing—fast—we needed more than duct tape and late nights.

So I decided to bring in the latest FP&A technology. Not a cheap decision. Not a small one. But I believed it was the right call. The pitch was solid: fast implementation, seamless integrations, and reporting that would make our board swoon.

Implementation was supposed to take six weeks.

Six. Months. Later…

We were still stuck in configuration hell.

And when we finally turned it on, the output was so clunky my team had to rebuild the reports in Excel just to explain them to operators.

It was one of the most frustrating experiences of my career—and one of the most important.

Because it taught me two things I’ll never forget:

1. Spreadsheets aren’t going anywhere. They’re still the fastest, most flexible way for finance folks to explore data. Like it or not, they’re our native language.
2. But spreadsheets can’t do everything. They’re not built for collaboration. They don’t tell the story behind the numbers. And when you’re leading FP&A, that story is everything.

So I stopped thinking about tech as a replacement. And started thinking about FP&A as a strategic function.

Here’s what that looks like—and why high-growth companies need it sooner than they think.

Growing Pains Come With a Price Tag

When a company’s scaling, it’s tempting to delay bringing in FP&A.

“We’re not ready.” “The ops team has it handled.” “We’ll hire finance after the next round.”

I’ve heard every version—and lived most of them.

But here’s what I’ve learned: the longer you wait, the more expensive it gets.

Missed margin targets. Blown headcount plans. Botched pricing experiments.

It adds up fast.

The Moment You Feel Chaos? That’s When You Needed FP&A Yesterday

Here’s the quiet signal you’re overdue: planning starts feeling political.

• Sales wants more headcount.
• Product wants faster velocity.
• Marketing wants more budget.
• Leadership wants alignment.

And the spreadsheet can’t tell you what trade-offs make sense.

That’s where FP&A earns its keep—not just crunching numbers but helping the business make choices.

Good FP&A Asks Better Questions

When we started investing in FP&A seriously, we stopped answering questions and started defining them.

Every planning cycle now starts with:

• What assumptions are changing?
• What’s the real driver of our burn?
• What happens if revenue misses by 10%?

The model is a tool. The conversation is the value.

Table: FP&A Impact by Growth Stage

I Wish I’d Brought FP&A In Sooner

Honestly? We thought we were too early. But by the time we brought in our first strategic FP&A hire, we were already behind:

• Budgets had no ownership
• Revenue planning was a black box
• We were optimizing top-line while margin eroded quietly

The first thing that FP&A helped us do? See.

Really see.

Where we were bleeding. Where we were guessing. Where we were defaulting to historical inertia instead of data.

Don’t Build the Model to Calculate—Build It to Clarify

This mindset shift changed everything for us.

Old model: calculate runway, produce a board deck, cross fingers.

New model: clarify trade-offs, test decisions, tell a story.

You know you’ve hit FP&A maturity when your forecast isn’t a report—it’s a conversation starter.

The Best FP&A Teams Don’t Just Forecast—They Shape the Future

Great FP&A isn’t reactionary.

It’s proactive. It brings optionality to leadership. It closes the loop between business inputs and financial outcomes.

It’s not about catching mistakes. It’s about asking what’s possible.

Final Thought: It’s Not Too Late. But It’s Probably Not Too Early Either.

If you’re wondering whether you need FP&A—you probably do.

Bring it in when:

• You’re planning headcount across multiple teams
• Your board asks for scenario analysis and you panic
• You start getting inconsistent answers about runway

The longer you wait, the longer it takes to clean things up.

What you need isn’t a perfect model. You need a partner in finance who can help your company make better decisions, faster.

The tools help. But FP&A is a mindset before it’s a team.

And that mindset? That’s the hidden edge most growing companies never realize they needed—until it’s too late.

If you’ve ever felt behind, or watched your team boomerang back to Excel, I see you.

You’re not broken. You’re just ready to lead differently.

Let’s make finance strategic again.

The most painful thing? The same five mistakes keep showing up. And they’re not just rookie errors. I’ve seen Big Four veterans make them. I’ve seen MBA-wielding CFOs overlook them. They’re everywhere.

This post breaks down the five most common mistakes I see in financial models—and how to fix them before your board deck blows up or your investor walks.

Mistake 1: Confusing Growth With Scale

Growth is easy to model. It’s linear. It’s a nice little uptick from last quarter’s sales. Scale? That’s harder. That’s where your costs don’t behave. Your ops break. Your unit economics wobble.

What I See:

• Revenue jumps 3x, but COGS and fulfillment costs stay flat.
• Headcount grows, but there’s no corresponding uptick in tools, training, or benefits.
• Models assume revenue per head stays static—even as roles shift from generalists to specialists.

Why It’s a Problem:

It creates a fantasy world where companies triple ARR without breaking a sweat. Investors might not catch it right away. But when they do? You’re labeled unserious.

How To Fix It:

• Build expense drivers into your scaling logic (e.g., customer support ratios, sales ramp assumptions).
• Layer in operational breakpoints (e.g., warehouse capacity hits max at 10K units/month).
• Tie scaling costs to departmental KPIs, not just headcount.

Real-World Fix:

In one model I reviewed, a SaaS company expected to triple users but kept server costs flat. We refactored AWS spend to scale by user bandwidth needs. Result? A $4M opex correction—and a model that passed investor scrutiny.

Mistake 2: The Assumption Avalanche

This one’s sneaky. A model looks clean. Numbers flow. But buried inside are assumptions stacked like Jenga blocks—and no one’s mapped what happens when one slips.

What I See:

• Assumptions hard-coded into cells instead of referenced from a driver tab.
• Scenario planning? Nonexistent.
• One optimistic sales ramp drives the whole castle.

Why It’s a Problem:

Assumption drift happens fast. What worked at Series A collapses at Series B. If you can’t toggle key drivers in real-time, your model becomes obsolete the moment conditions change.

How To Fix It:

• Centralize all assumptions in a dedicated input tab.
• Use dropdowns or flags to drive scenario logic (base, upside, downside).
• Pressure test inputs monthly with real data.

Table: Example Assumption Audit Checklist

Mistake 3: Timeline vs. Time Logic

Time logic is what separates spreadsheet hacks from financial operators. Most models are built with timelines—they tell you when something happens. Time logic tells you how it happens.

What I See:

• One column per month, with manual entry of data.
• Revenue recognition based on invoice date—not delivery or accrual.
• Cash burn modeled as straight-line instead of reflecting AR/AP cycles.

Why It’s a Problem:

You end up with beautiful models that misstate runway by six months. Or worse—burn multiples of capital before realizing it.

How To Fix It:

• Use time-based formulas: EOMONTH, OFFSET, and logic for delayed effects.
• Separate accrual and cash logic explicitly.
• Model working capital shifts: when cash actually enters or exits.

Real-World Fix:

A PE-backed ecommerce brand modeled cash conversion as T+0. When we added 45-day vendor payables and 30-day receivables, the cash flow timing shifted so dramatically they renegotiated their credit line.

Mistake 4: Ignoring the Story Behind the Numbers

Here’s where models fail to resonate. They’re correct but irrelevant. They don’t match the narrative. They don’t speak to the operator or the investor.

What I See:

• KPIs buried five tabs deep.
• No dynamic summaries that tie results to strategy.
• A model that’s technically flawless but tells no story.

Why It’s a Problem:

The best models sell a vision. They answer: Where are we headed? What will it take? Why does this matter now? Without a story, your model is just a math puzzle.

How To Fix It:

• Create an executive summary tab: revenue, burn, EBITDA, CAC, LTV, cash runway.
• Tie your model outputs directly to board questions and investor priorities.
• Use visual tools (charts, heatmaps, flags) to highlight trends.

Mistake 5: Overengineering Instead of Operating

This one hurts because I’ve done it. We’ve all done it. You build a gorgeous, multi-tab, cross-linked monster. And no one uses it.

What I See:

• VBA scripts that break during copy-paste.
• Dozens of tabs with overlapping logic.
• A model that looks like it should be in a museum, not a boardroom.

Why It’s a Problem:

Your job isn’t to impress Excel. It’s to help the company make better decisions. If only you can operate your model, it’s not a model—it’s a liability.

How To Fix It:

• Kill vanity complexity. Simpler = scalable.
• Make your model self-documenting with notes, formatting, and tooltips.
• Test it with someone else: can they run a scenario in 2 minutes?

Pro Tip:

I always do the “coffee test”: I hand the model to a peer, go make coffee, and see if they can figure out the drivers before I return. If they can’t—it’s too complex.

Final Thoughts: Build for Clarity, Not Control

The best financial models I’ve seen aren’t the flashiest. They’re the most useful. They help a CEO understand what happens if churn ticks up. They help a CRO see how an extra rep moves the forecast. They help a CFO sleep better.

Build your model so that someone else can live in it. Strip out ego. Add transparency. Embed logic. Then pressure test it like your career depends on it—because it just might.

That’s what separates a good modeler from a strategic finance partner.

And that’s how you get invited back to the table.