And sometimes that means I get to wrangle with the technique of writing scenes out of order.
Putting them all in chronological order and creating two stacks -- those that I have slithered into their proper place, and those I have yet to reach -- helps because when I shift to a new scene, I can check the top of the pile and see whether I've already written it yet.
Then again, sometimes that brings me nose to nose with stuff I wrote before except that obviously, the gremlins have been at it. Such dull, stale, and profitable prose. . . .
And so I end up re-writing the scene as if I hadn't realized that scene was there.