The pulsations in the intake manifold from individual intake strokes makes a PCV valve take small sips of air out of the crankcase, not a constant flow. The plunger inside is designed to almost completely cut off the flow at times. There are also a few different designs of PCV, depending on the displacement of the engine it's used with and the volume of flow it allows.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!