It is a building block skill that is more important in our sport than many divers realize. Unfortunately I see recreational divers through the master scuba diver level that still are in poor trim with little control and that kick up silt while burning through tanks. Fortunately those heading towards the pro ranks are required to pass more ridged requirements for buoyancy control and learn to properly trim and hover. Should it be part of the OW experience? It is but testing only requires an understanding and basic skill level. IMHO this is probably as it should be but certain specialties should have prerequisites of advanced and that should contain the full PPB class and more stringent requirements. It is my assertion that Advanced Diver Certification should not be only an experience builder but contain the skills checkout at an advanced level. Combine the full specialty level training of PPB, Nav, Deep and Night thus creating a diver who is advanced enough in their training to take on the extra tasks needed for specialties such as Cave or wreck diving.