My former writing teacher, the essayist and cartoonist Timothy Kreider, explained revision to me: “One of my favorite phrases is l’esprit d’escalier, ‘the spirit of the staircase’ — meaning that experience of realizing, too late, what the perfect thing to have said at the party, in a conversation or argument or flirtation would have been. Writing offers us one of the rare chances in life at a do-over: to get it right and say what we meant this time. To the extent writers are able to appear any smarter or wittier than readers, it’s only because they’ve cheated by taking so much time to think up what they meant to say and refining it over days or weeks or, yes, even years, until they’ve said it as clearly and elegantly as they can.”
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It’s normal (and even desirable) that the structure of your work will change drastically between drafts; it’s a sign that you’re developing the piece as a whole, rather than just fixing the small problems.