For clarification the only pilots getting relief lines are new hires and upgrades released from training that missed the bid deadline. Those lines are required to have 15 days off.
The original question was about average days off. Not sure what the historical average is in ORD or system wide, but there is nothing in our CBA that requires an average of 15 days off. That would be nearly impossible to do in PBS anyway. Min days off could be adjusted upward but currently it’s 13 for line holders and 12/13 for reserves for a 30/31 day month respectively.