The problem is that 99% of the time, when PO is working, it just works. A plat logs in, books the room, and goes on their merry way, never knowing they got a perk. Then they find a blocked date, call to get the override and it is denied and they post "The ONE time I REALLY needed an override and it wasn't available!!!"
If you have to call- it is because PO is blocked for that hotel/date and chances are it will be denied.