undercoating inside the doors and sound deadener

I heard from some other people that they installed the sound deadener over the factory undercoat. I have (4) sheets left so I'll put three sheets in the doors and call it good. Once the glass is in and all adjusted, I'll put the last sheet on the inner door skin. That's got a lot of noise to it when you tap on it. I think that might be worth it more then the outer skin. Thanks