So we give our designers a default role of Reviewer, because they are the person that uploaded the file so they don't need to approve it. The Reviewer status will not hold up a deadline if no one bothers to open it. The Reviewer/Approver will hold up the deadline. Also when a job has to be moved to a different designer because the original designer gets sick or goes on vacation, we have to do a twostep process. Step 1, highlight the document or proof and change the new designer's role to Author then we have to do Step 2 which is to give them management authority over that proof only. This is the only way a second version of the proof can be loaded on top of the first proof and be viewed side by side. Never use "Approver" because the person approving always something to say... (cough cough). Sometimes on the very last proof, after we have sent it to the printer and we just want to let the approver know it's gone, we will send it to one of the 15 or so approvers as a "Read Only". Just as a curtesy. Never use Moderator, don't have the need. There is a description on the help area about proofing roles.
https://support.workfront.com/hc/en-us/articles/115004177187-Understanding-Proof-Roles Samantha Senior Specalist, Creative Services 817-424-2186