In several places, and particularly in the final chapters, she discusses how her craft evolved over time as life experiences piled up alongside creative confidence. Here, she talks about the "hard earned craft of songwriting," but I think her point travels well across literary genres.
"…as I get older I have found the quality of my attention to be more important, and more rewarding, than the initial inspiration. This maturation in songwriting has proven surprisingly satisfying. Thirty years ago I would have said that the bursts of inspiration, and the ecstatic flood of feeling that came with them, were an emotionally superior experience, preferable to the watchmaker's concentration required for the detail work of refining, editing, and polishing. But the reverse is proving to be true. Like everything else, given enough time and the long perspective, the opposite of those things that we think define us slowly becomes equally valid and sometimes more potent. I have learned to be steady in my course of love, or fear, or loneliness, rather than impulsive in its wasting either lyrically or emotionally."Which to me means, more or less, that the more intimately you work within your craft, the more you work at "refining, editing and polishing," the better your writing will be, whether that's songwriting or fiction writing, or memoir writing. The part about coming to this knowledge after a certain number of years elapse, while certainly true for most artists, doesn't mean we all have to wait that many years to learn this lesson.
[Disclosure: Before I could act on my own to-be-ordered book list, I received a complementary copy of Composed from the book's publisher, Penguin.]