Why most financial models fail the moment your startup starts moving fast?

One thing I’ve seen over and over: founders build a financial model early on, then never touch it again.

Revenue changes. Pricing evolves. Costs shift. New hires, new markets, new investors—yet the model stays frozen in time.

The result?
• Decisions based on outdated assumptions
• Expensive consultants to “fix” models every few months
• Spreadsheets no one fully trusts anymore

This is one of the main reasons we started building ProformaGen.io—to help founders generate and continuously evolve financial proformas as the business changes, not just at fundraising time.

Curious how others here handle financial modelling as they scale.
Do you rebuild models often, or just patch the old ones?