Australian Standards for timber construction focus on nail length in the receiving member, rather than embedment of the nail head, since nail length in the 'second member', plus nail diameter, are the factors that govern the strength of the joint. If you are dealing with the nailing of a deck, nail heads should not be protruding above the surface of the decking as they will present a hazard to foot traffic. On the other hand they should not be over-driven to the extent that they are significantly below the surface of the decking as that creates a point for water to collect.