Thanks for the link. I have no idea who Ira Glass is/was, and will not look it up because I am a little busy now, but I believe what the text and voice are trying to say is “every writer has a first book that is barely readable but by the time the author puts out the 15th or 20th book the writer has improved so much the later books sell really well”.
I just had a funny thought.
I should do a video using the word “Practice” repeated over and over for the length of the video with small background font showing sales figures increasing throughout the length of the video, then end with “Doh!” (I think that was what Homer said in the Simpson cartoon my kids watched.) Too funny.