You shouldn't take extra. That just creates resistant parasites, and it doesn't get rid of them any faster or better. Dr. Bailey tells us all the time that this is a slow process, and no overnight cures.
That being said, I get impatient and anxious for it to be over too, as we all do, but think of it like having diabetes. You wouldn't think that taking more insulin for a shorter time would cure you, so don't think of this like that.
Just take as directed and be patient.