How do I practice planning fallacy?

Next, run a five-minute pre-mortem: assume the project has already failed to meet its deadline, then write down three to five specific reasons why. For each reason, add a time buffer or a mitigation step to your plan. Finally, calculate your personal multiplier by dividing the actual duration of your last three completed projects by their original estimates. Apply that multiplier to your current estimate. The number you end up with will feel uncomfortably large. That discomfort is the planning fallacy losing its grip.

Common pitfall: Turning countermeasures into cynicism. The point is not to assume everything will be a disaster and pad every estimate with so much buffer that you never commit to anything ambitious. The point is to replace optimistic fiction with calibrated realism. Over-buffering is its own failure mode — it breeds complacency, kills urgency, and makes you the person who always under-promises and under-delivers because they never push themselves. The goal is accurate forecasting, not pessimistic forecasting. You want your estimates to be right, not just safe.

This practice connects to Time Systems — building it as a repeatable habit compounds over time.