Since we're on the topic of peel dust, while a lot of people think it is just a matter of preference as to what is used as a peel dust, it is actually a lot more than that. A soft dough, one that has a high dough absorption, when placed onto a peel with just flour will tend to hydrate that flour quite fast, thus losing the slip characteristics provided by the flour. In this case something that won't hydrate as fast is needed, this is where semolina flour comes into play (it hydrates very slowly). If the dough is really wet, as some are, corn meal will help to actually hold the dough off of the peel surface, thus facilitating slip. In actual application, we seldom ever use 100% of any of these products, but instead, use a blend of them to make our peel dust, which is all based on the properties of the dough that is on the peel at the moment. My own personal favorite blend is made from equal parts of regular flour, semolina flour, and fine grind corn meal, and I've yet to have a pizza stick to a wood peel when I did my part. By the way, you are absolutely correct, shaking the dressed dough skin on the peel occasionally before taking it to the oven is vitally important to ensuring a release every time regardless of what you're using as a peel dust.
Tom Lehmann/The Dough Doctor