Unless you’re writing instructions or technical copy, writing is a creative process. When writers are in the flow, they work in bursts of energy, hammering out paragraphs without stopping to think about editing.
Unedited writing is, in the words of Annie Lamott: shitty. And so it should be. If you’re stopping every three words to check what you’re doing, you’re going to take days to write a disjointed, awkward piece. That’s where using an editing checklist comes in.