# L

The share of a design's usability problems a single test user finds (31 percent on average in Nielsen and Landauer's projects, per the article).

**Source:** “Elaborate usability tests are a waste of resources. The best results come from testing no more than 5 users and running as many small tests as you can afford.” [Why You Only Need to Test with 5 Users (Nielsen Norman Group)](https://www.nngroup.com/articles/why-you-only-need-to-test-with-5-users/)

See also: [Usability problem](/reference/glossary/usability-problem).

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Published 2026-10-29. Web page: https://www.mackenziebowes.com/reference/glossary/l