Editing an audio book is a lot like personal growth. It's tedious, and you notice mistakes. Do-overs are necessary. Sometimes pacing is inconsistent. But, when it's all done, you look back and think, "wow. That's really good."
I am currently editing chapter 31 out of 52 on the audio book. I'll have to do some re-records, as I said the wrong word a few times and decided to change a line in the story.
But, that's just like growth, isn't it? Progressing slowly, but surely. But always moving forward and getting better.