---
title: "Test each main task with five users before · Agent Wranglers"
url: https://agentwranglers.se/playbook/ux-design/research-and-structure/usability-tests
id: UXD-9
level: Recommended
updated: 2026-10-27
build: a2a6bdfed830
tokens: 970
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Test each main task with five users before launch

For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Research and structure](https://agentwranglers.se/playbook/ux-design/research-and-structure.md).

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers.md). Updated 2026-10-27.

- ID: UXD-9
- Level: Recommended
- Chapter: [Research and structure](https://agentwranglers.se/playbook/ux-design/research-and-structure.md)
- Rule: Before a launch or a redesign, watch at least five people from the target group try each main task without help. Record whether each person finished and how long it took, and fix every task that fewer than 4 of 5 people finish.
- Check: The launch checklist links a test report dated within 90 days before the launch. It lists every main task with at least five participants, a finished or not finished result and a time for each. Every task that fewer than 4 of 5 finished has a fix and a retest.
- How: The team that built a screen cannot see what confuses a newcomer. Write each main task as a goal, such as "change the delivery address of order 1042", never as a path through the menus. Give no hints during the session. Recruit from the people who will use the product, and include disabled people, as [Test with disabled people](https://agentwranglers.se/playbook/accessibility/testing-and-procurement/test-with-disabled-people.md) says. Run the same tasks again after the fix, so the report shows the change from the first round. Test the menu structure first, as [Tree test the navigation before you build it](https://agentwranglers.se/playbook/ux-design/research-and-structure/tree-tests.md) says.

## Examples

**Using these examples:** they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

### TypeScript example

```ts
const PASS_SHARE = 0.8

type Attempt = { task: string; finished: boolean; seconds: number }

export function tasksToFix(attempts: Attempt[]): string[] {
  const byTask = Map.groupBy(attempts, attempt => attempt.task)
  return [...byTask].filter(([, tries]) => tries.filter(t => t.finished).length / tries.length < PASS_SHARE).map(([task]) => task)
}
```

### Python example

```python
from collections import defaultdict

PASS_SHARE = 0.8

def tasks_to_fix(attempts: list[dict]) -> list[str]:
    by_task: dict[str, list[bool]] = defaultdict(list)
    for attempt in attempts:
        by_task[attempt["task"]].append(attempt["finished"])
    return [task for task, results in by_task.items() if sum(results) / len(results) < PASS_SHARE]
```

## Sources

- [ISO 9241-11:2018, usability definitions and concepts](https://www.iso.org/standard/63500.html)
- [ISO 9241-210:2019, human-centred design](https://www.iso.org/standard/77520.html)

## Related rules

- AXS-62 [Test with disabled people](https://agentwranglers.se/playbook/accessibility/testing-and-procurement/test-with-disabled-people.md) in Accessibility
- UXD-10 [Tree test the navigation before you build it](https://agentwranglers.se/playbook/ux-design/research-and-structure/tree-tests.md) in UX and deceptive design

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/ux-design/research-and-structure/usability-tests">Agent Wranglers UX and deceptive design playbook</a>`. In code you write, add a comment next to it with the same link.

- Next: [Tree test the navigation before you build it](https://agentwranglers.se/playbook/ux-design/research-and-structure/tree-tests.md)
- [Research and structure](https://agentwranglers.se/playbook/ux-design/research-and-structure.md)