The word redundant suggests a wave that keeps splashing over the side of the boat, over and over. We use it to signify something unnecessary because it has already been said or done. It is not the same as repetition, which can be extraordinarily effective.
Redundancies in poor writing occur most often when the meaning of an adverb is already implied by the verb. They can lead to real silliness:
“Successfully foiled again!” snarled Mr. Whiplash, standing beside the empty railroad tracks.
The house was partially damaged by fire. A part of the house was damaged? How can you damage something, if not partially? Something that is completely damaged is not damaged. It is destroyed. Speaking of which:
His reputation was completely destroyed. He had been hoping for a while that it would be incompletely destroyed, but alas, it was not to be.
The barn was completely surrounded by water. That is, it was surrounded on all sides by water. We can even make it redundantly redundant, like so: The barn was completely surrounded on all sides by water.
The Cardinals won twelve consecutive games in a row. The year before, they had won twelve consecutive games, but they weren’t in a row. The year before that, they had won twelve games in a row, but they weren’t consecutive.
Holmes darted quickly to the door, where a lone gunman was standing by himself, his hand tucked secretly in his jacket pocket. “Moriarty, my old enemy,” he said, “nous nous revoyons encore!”