Not totally: if you had a wide open, constant diameter hole from the cam up to the rocker shaft, it would get a LOT more out out than really gets to the rockers in the factory design at low and mid RPM's. The other restrictions regulate those 'spurts' from the cam's 'oil flow interruptor' at low and mid RPM's. At high RPM's the oil flow is limited more by the oil's mass, viscosity, and inertia; it had to accelerate from a dead stop each cycle, and just can't 'get moving' during those very short 'windows' of flow. (Which I think you have mentioned from time to time.)