Shortening a document can make its main decision easier to find. Keep the context necessary to interpret that decision correctly.
Identify the reader, the task and the consequence of misunderstanding. Preserve definitions, assumptions and essential qualifications close to the claim they support. Move secondary detail into an accessible supporting location where appropriate.
Test the reduced version
In a fictional management summary, a single figure labelled hours saved may hide that it represents estimated capacity under assumptions. A shorter explanation that preserves this basis is more useful than an impressive headline stripped of its meaning.
Ask a suitable reader to explain what the summary permits them to conclude. Notice where their interpretation exceeds the evidence. Restore the missing context or improve the wording.
Remove repeated information and material unrelated to the reader's decision. Keep a route to the source for people who need to investigate. Clarity comes from choosing the right information and arranging its relationships well. The shortest possible version is useful only when it still supports an accurate understanding of the work.