Some organizations (usually very small ones), may simply want to allow all employees to review a given colleague. Rather than adding every single person to the participant list, you can simply use the advanced options link and select "Open feedback: Allow anyone in the organization to participate in this survey"
When this option is used, each person in the organization has one single item in their Tasks list, rather than having multiple reviewees who they may or may not actually intend on filling out their survey.
After pressing Select Reviewee, the user will then be taken to a separate page with all the possible reviewees from that cycle. They can push Get Started on the ones they want to fill out and ignore the rest.