Steady or bobbing head?

I guess the ideal is she who does both during the same blowjob. Bobbing, sometimes shaking, occurs best when she has taken me to the balls, even started licking them while she sucks my cock. I like her to treat it a bit like a dog does a rag -- shake it, and growl even, before the excitement makes me cum. And she doesn't come up on my cock but continues her frantic little movement as I shoot into he throat. Now that's cocksucking!