Generally, all contractors have 7 days from the date they check out work to complete it. However, the send-back process can extend this as expert writers and reviewers collaborate. People may also be offline for a period of time and miss the notification that an asset was returned for additional work or correction.
Returned assets in a reviewer's work queue does not prevent the reviewer from checking out more work and completing reviews for other assets. If it has been longer than a week since you returned an asset to an expert writer and you have not received any communication from the writer, you can submit an Answers Issue Form, selecting the option "Writer is unresponsive to/disagrees with revision requests."