In programming, it's usually accepted that DRY code is better code in most situations.
Does this principle also apply to documentation?
I'm asking about the documentation output, not necessarily the source material (there are tools for keeping the source content DRY even if there's a lot of repeated content).
Example: suppose I have the following content:
- Some task
- Prerequisite setup task
- How to do X
- How to do Y
Should "How to do X" and "How to do Y" explicitly say "Before doing this, make sure to do Prerequisite setup task"? What are some good rules to follow when deciding if documentation should repeat itself?
I intended this question to be about end-user documentation. In some context, such as code or compliance documentation, the answer may drastically change. See Chenmunka's answer for some of those implications.