I’ll let you in on a little secret: Writing at the speed of light isn’t as hard if you have your technique down cold. Of course, you have to have a grip on the technique, and that’s what trips up most writers in the first place, right?
We have the vision. We’re swimming in creativity. But we’re drowning in our own need for perfection. Word of advice: Let it go. No matter what words you choose, regardless of the voice and tone you select, no matter how carefully you craft the style, you will never achieve perfection. So get over it. If you don’t, you will never get the words on the page written and the work out the door.
The speed of light technique: Focus, write, revise. At some point you have to decide that your work is actually finished and move on.