I don't shake it like it owes me money... thats what I wasted money on Oxygen and a stone for. So I oxygenate, then shake till I'm bored of shaking (about 15 secobds). Anyway, it gets me more yeast than the stirplate and it smells totally fresh and tastey, as compared to rank yeasty stirplate stuff. Works for me.
All of my ales get 2L of 1.030 and one smack pack per 6 gallons, lagers get two of those per 6 gallon. Amounts subject to change when dialing in a specific recipe. Someone may say thats too much, and I would say yes it might be. But the effects of too much are far less noticeable vs too little. Though, one might want too little or too much (at least compared to a calculator) depending on desired effects.