MENTAL MODEL · M3709

Time-Saving Bias

DecideHigh supportDecision Science

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Updated 2026-08-05

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INTRODUCTION

English translation pending.

CORE DEFINITION

A judgment bias in which people extrapolate linearly from speed to time saved, overvaluing improvements at high speeds and undervaluing them at low speeds. The relationship is hyperbolic: raising speed from 20 to 40 km/h halves travel time, while going from 100 to 120 km/h saves only a sixth. It applies to any throughput or travel task whose metric is elapsed time rather than distance covered.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

- Bottleneck targeting: optimize the slowest step first, where time gains are largest. - Marginal check: stop investing effort in steps that are already fast. - Intuition correction: compute the time saved rather than estimating it from the speed number.

anchor

Anchor fast decisions

Time saved equals the old duration minus the new duration, which is inversely proportional to speed. Because the curve is hyperbolic, equal speed increments produce shrinking time gains as speed rises. People instead reason linearly from the speed number itself, so intuition systematically misallocates improvement effort toward the steps that are already fast.

MINIMUM ACTION

In progress 0/1

Practice this model in one real situation:

Compute the time saved for each candidate improvement instead of guessing. 2. Rank the candidate improvements by the time each one saves. 3. Improve the slowest step in the process first. 4. Stop optimizing steps that already sit near the top of the curve. 5. Recompute after each change, since the bottleneck moves.

Check to track your progress (stored locally)

Learning progress0%

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Source support: Explicit

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en.wikipedia.orghttps://en.wikipedia.org/wiki/Time-saving_biasZH · Explicit
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