Planning Fallacy

The planning fallacy is the tendency to predict unrealistically short timelines and low costs for work you will do yourself, while treating others’ delays as unsurprising.

You rely on best-case scenarios and unique-case stories, not on how similar tasks actually finished before. That feeds late nights, broken commitments and decision drift when reality arrives.

Stronger practice: anchor estimates on past data or comparable projects, add explicit buffers and define definition of done before you commit. Parkinson's law explains why open-ended time expands; pairing honest forecasts with time boxing keeps scope and schedule honest.