This setting has two options when enabled for the shift: Next Day Off and Previous Day Off.  If the Next Day Off option is selected then if agents have this shift, they get the next day off. If Previous Day Off is selected, then if agents have this shift they get the previous day off. One example of where this might be a valuable rule to add is when you have a shift with fewer days but longer hours. In this case, you may want to ensure a day off after a long shift.