Platform Centre Offset - which way to move cleats if +10 on both pedals?

I know it is a bit random but I seem to have between +10 and +14 on both shoes and although PCO is not the be all and end all of cycling efficiency I can't help but think I am pushing too far out on the pedals. I should move the cleats both more laterally by about a cm I think? That would bring the shoe nearer to the BB and reduce the PCO to near zero. Or am I missing something?