There may be writers who take half a day to decide where a comma should be placed in the wip, and there may be those who write sixteen thousand words in a day. It doesn’t follow that the former is a better writer or that one finished product is better than the other.
"Efficiency" and writers don’t seem to naturally go together. Words like “muse” creep into conversations. I agree with the writer who said that the slowest and dullest writing happens when she didn’t know what happened next in the story. The reason was because her writer's instinct didn't know what they should be trying to do, and so the right words failed to materialise. I agree: it makes an astonishing difference to my writing if I know what’s going to happen, and – just as important - why it is happening.
Thinking time is valuable. One writer said she found time at the ironing board great for thinking out wriggles in the plot, so the next time I had the ironing board in place, I started thinking about my next chapter. Before I finished ironing the shirt, my mind had wandered to what I was going to cook for dinner. I wrenched it back to plot, and began another garment. Before I completed a sleeve, I was thinking about my last holiday and my next holiday, anything but plot. I need the discipline of sitting down at the computer to concentrate my mind so I do a few notes, or a chapter outline. A few notes about the progression of a scene works for me, too, and saves that awful feeling of getting triumphantly to the end and then realising you’ve omitted the most important fact of all. But if you can focus on plot while doing something else, do, because it is an invaluable skill.
Something else I’ve noticed is that writing about certain characters is easier than others. I assume that means I have more empathy with the character who comes to the page more easily. Subsidiary characters ought not to be cardboard cut-outs, but they are understandably less charismatic than the leading characters.
Most important of all - it’s important to get the story down, to have a first draft that you can then edit. To write effortless prose while working out a plot-line is something only the few can do. Editing too early in the process can soon stifle the flow. No matter how much the story changes as you charge along, getting to the end is vital. You can always go back and edit, as long as you have something to edit.