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The Planning Fallacy
People are usually overly-optimistic when estimating the time required to complete a task.
Similar psychology:
Last updated: 03/11/2026
How to utilise this in your designs
If someone tries to quit an account opening flow part-way, you could tell them how much longer is left, so a flow that's overrun their optimistic estimate feels finite.
Example from
WeBull
Try showing how long it'll take to reach the overall goal at the weekly pace users pick, so their plan rests on a realistic timeline, not an optimistic guess.
Example from
Food Llama
When someone tries to end something that's slow to get going, e.g., a room nobody has joined yet, it may help to remind them it can take a while for people to arrive.
Example from
Clubhouse
When people estimate their own ability, consider pre-filling answers from their past results, e.g., previous running times, so they plan from what happened, not a best case.
Example from
Runna
One option is to show how achievable a monthly goal is as it's set, so people can scale back an overly optimistic plan before they start.
Example from
Headway
Possible impacts
Realistic time estimates upfront could help keep users motivated, as a task that runs to plan feels less draining than one that overruns their optimistic guess.
Because users tend to underestimate how long things take, showing realistic waits upfront might reduce frustration when a task runs long.
When a long form overruns the time users planned for, they may rush later answers or accept defaults, which could lower the quality of the data you collect.
Users may abandon a flow that runs longer than they planned, so showing how much is left could help more of them finish and convert.
Written by Peter Ramsey
Published: