In Oz all licenses are revalidated when the highest, ATP, is renewed. In the case of a pilot requiring six monthly medicals, his/her ATP will "fall back" to CPL after the due date of the ATP six monthly. If all you need is CPL, that's fine and beaut. This applies to pilots over sixty as I recall it, until then twelve months is the time for ATP medicals.
Be aware that I know next to nothing about the FAA rules!