User story cards can help you identify your users and their tasks. They're an easy way to do a little planning to help guide your writing.
Web writers sometimes say there's no point planning content. Content approvers make so many changes that planning time is wasted. Sounds reasonable, except there's a flaw in the logic.
Lack of planning leads to content that lacks a focus or clear purpose. Asking the right questions before you start writing will help you write better content.