Proof planchets were not rough. I am not really sure of your question? Proofs were struck with specially prepared planchets and dies. Proofs were also struck twice and at a higher pressure to ensure quality.
I see, but the pressure of the die changes the planchets and can smooth them out, and even created frosted devices etc. It helps mightily that the planchet is right to begin with. I have no first hand experience with minting coins, so i can't really say as a fact from first hand experience. I only know what I read.