Can't comment on the mechanical aspect (the fluttering), but I would say that iIf you are saying you're doing, or aiming at, 30 in/out cycles per minute, which sounds to me like hyperventilating, I'd say that's not the typical way of doing it. If that works for you, I'm surely not going to tell you it's wrong. The more typical model is deep inhale/hold a second or two/full exhale with crunch to expel as much air as possible. (Here, too, people discover variations of the tempo that works best for them.) I think I do remember seeing @Racer1_NC demonstrating and kind of fast inhale/exhale in a video . . . so I could be wrong about how common that method is.
Batch, another oxygen expert, reccomends ten 3-second very deep/forceful in/out cycles with room air, followed by a deep inhale of the pure O2 and holding it for 30 seconds with a crunch exhale, and then back to the room air hyperventilating for 30 seconds, then back to O2 from the tank, etc.