There is no specific number that denotes how many outreach articles your website may need. Publishing many outreach articles is also not commensurate with having a high domain authority. For instance, receiving a do-follow backlink from one 90+ DA/DR website may go a longer way than earning links from two 20+ DA/DR websites.
It’s expedient to work with outreach professionals who can assess your website’s needs. They can set a target of where you should be and determine the appropriate number of links that will get you there. Performing competitor analysis can also help them determine how many outbound links you should receive on your content.