Planning Fallacy
Version 1.0.0 · Updated 2026-07-30
CORE DEFINITION
People tend to be optimistic (underestimate) when estimating the time required to complete their own tasks, even if they have always been delayed in the past. Because when planning, we only consider the 'smooth path' and ignore 'unexpected disruptions'. Scaffolding role: The rule of thumb for schedule padding. When making plans, refer to 'Reference Class Forecasting': look at how long others took for similar projects, rather than how long you think it will take. Or simply multiply your estimated time by 2.
SCAFFOLDING EFFECT
Reduce cognitive load
The rule of thumb for schedule padding. When making plans, refer to 'Reference Class Forecasting': look at how long others took for similar projects, rather than how long you think it will take. Or simply multiply your estimated time by 2.
Anchor fast decisions
Kahneman and Tversky proposed that people systematically underestimate the time, cost, and risk required when making plans, due to over-reliance on idealized scenarios.
MINIMUM ACTION
In progress 0/3Practice this model in one real situation:
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Source support: Explicit
- zh.wikipedia.orghttps://zh.wikipedia.org/wiki/%E8%A6%8F%E5%8A%83%E8%AC%AC%E8%AA%A4verified
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