CM 9.3 Document Review feature

Upgrading to 9.3.1 - Have seen a new feature (from 8.3) called Document Review. Can anyone assist in advising what the feature might be used for, what kind of records might need to be reviewed, and what gap it is filling. I have found it a little confusing, particularly at the individual record level. For instance, there is no mechanism to send an email to reviewers or authorizers if not not completed at the record level, only the record type level