Well, even though your title is deliciously click-bait (No, you didn’t write a SUCCESSFUL Medium story in 10 minutes, you wrote a successful first draft), I agree with your methods. Write it out, let it mellow, put on your editor’s cap, work it, work it, work it, let it mellow, read it as the reader who has no idea where you’re going, fix it if you need to, then PUBLISH many hours or even days later.