In Outliers: The Story of Success, Malcolm Gladwell suggests it takes 10,000 hours of practice to get good at something. Gladwell grounds this claim in his interviews with successful writers and review of scholarly conversations on the topic.
It’s hard to say how long it takes to become a successful writer. People seem to vary. And even highly successful authors—the sorts of folks who are interviewed by The Paris Review, a literary magazine that publishes interviews of famous writers—talk about writing as a lifetime apprenticeship.
One things seems certain, though: becoming a successful communicator takes loads of practice.