MENTAL MODEL · M1527

Project Management Triangle

BusinessHigh supportManagement

Included

Version 1.0.0 · Updated 2026-07-30

CORE DEFINITION

Scope, Time, and Cost. These three are mutually constraining; you can only pick two (Good, Fast, Cheap - Pick two). Quality is often seen as the area enclosed by these three.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Reject impossible promises. When the boss demands "more, faster, better, cheaper," draw this triangle for him. To be fast and cheap, you must cut features (scope); to have full features and be fast, you must increase cost. Physical laws cannot be violated.

anchor

Anchor fast decisions

Scope, time, and cost are mutually constraining; any change in one will affect the others. Quality can be seen as the area enclosed by the three; compressing any side will sacrifice area (quality) or require compensation from the other sides.

MINIMUM ACTION

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Practice this model in one real situation:

When facing new requirements, first identify which side of the triangle it changes
if "more, faster, better, cheaper" is demanded all at once, point out the impossible triangle and force trade-offs
use the "pick two" framework to negotiate constraints with stakeholders
treat quality as a protected area.

Check to track your progress (stored locally)

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Source support: Explicit

link
en.wikipedia.orghttps://en.wikipedia.org/wiki/Project_management_triangleZH · Explicit
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