I am a terrifically fast writer. If I have a report to write (or better yet, substantially edit), you will find me in a little private world of my own, pounding away on the keyboard.
This usually works well - I can save a ton of money on my projects by finishing summary reports in record time. But in the mid-winter doldrums, I need to remember that a consultant is paid by the hour, not by the report. And if I finish my writing too early, then I will have nothing else chargeable to do. I used to get scolded because I would finish far too quickly, screwing up the budget in the wrong direction, making my more casual workers work bad, and requiring continuous new assignments.
I'm getting better at this sort of thing. I usually write at my usual fast pace, and then spend lots of time polishing it to a fare-thee-well. And if I'm looking at a long block of time with little work to do, well, there's always the "drink lots of water and then take thirty bathroom breaks" method.