There are several strategies and tools you can use to manage the systematic flow of contracts, briefs, content approvals, and other documents during your campaign:

1. Document Management Systems (DMS): A well-organized DMS helps you keep track of all documents in one place, ideally with version control. Systems like Google Drive or Dropbox offer simplistic solutions.

2. Project Management Tools: Tools such as Asana, Trello, or Monday are often used for managing and tracking tasks related to contracts, briefs, etc.

3. CRM Platforms: Platforms like HubSpot or Zoho provide a more comprehensive view of the campaign process, from initial contact to final campaign completion.

4. Influencer Marketing Platforms: Some platforms provide built-in document management features. For instance, Flinque helps brands and agencies manage contracts, content approvals, and other essential documents through one streamlined platform.

It’s important to note that the suitability of these tools depends on your needs, resources, and the scale of your influencer campaigns. A small brand running a one-off campaign might find Google Drive sufficient, while an agency managing several campaigns concurrently might require a more robust solution like Flinque.

Remember, using these tools effectively requires not just choosing the right platform, but also maintaining a disciplined workflow. Routine status meetings, clear delegation of responsibilities, and enforcing strict adherence to document naming conventions are all vital strategies to manage document flow. You should also leverage platform features wherever possible, such as the content approval process in Flinque, to enhance efficiency and avoid the confusion of working through disparate channels.