So fierce is the competition to impress the leading publishing houses, that many literary agents offer editorial advice to their clients. Their submitted manuscript may very well have done enough to catch the agent's eye, but surviving the critical eyes of a publisher is an altogether different proposition.
As a result, the notes that agents can provide authors can be the difference between making it through to the Editorial Director or failing to make it past the Assistant Editor.
The advice itself is often related to tightening the story so that the polished draft is superior to the one that first secured representation.
The clients hang on every word the agent bestows because having come this far they do not want to be rejected at the final hurdle. The will tirelessly rewrite and perfect their manuscript until their agent feels it is ready to submit to publishers.
But the inherent problem with writing advice is knowing which advice best fits the story and which distracts the reader from the story, because not all advice benefits a manuscript.
This is an idea explored in this sketch from the television show That Mitchell and Webb Look as a literary agent offers contradictory writing advice to their client.