Because checklist items are either hot or cold (mandatory or non-mandatory), Reviewers can forget the checklist entirely when checklists are non-mandatory. Our use case is that out of the checklist items some may not apply to the current review, so we are forced to make them ALL non-mandatory.
There are several approaches to the problem, two come to mind.
1) if no check list items are checked; ask did you forget to review the checklist items dialog box?
2) allow individual items on the check list to be mandatory or non-mandatory.