Not every piece will need extensive revision, but most articles and pages will probably fall into this category.
Some content will need refreshing, such as updated statistics, screenshots, or product information. You may also want to improve pieces’ SEO potential with smaller updates like metadata, internal linking, or a fresh « updated on » date.
Other pieces will need complete rewrites, either because of published information or incorrect references to your website as you’ve continued to develop and grow it.
There may also be other types of content that are perfectly fine, but require new (or improved) calls to action.
A great way to see where you need to improve your content is to category it into buyer’s journey stages, as in this example: