The first 90% of any of my projects consists of getting something -- anything -- working. As I usually underrate the complexity of the problem and overrate my ambition to solve it, time drags on.

By the point of 90% completion, I move into a polishing sort of mode, where I remove the awkward bits and refine sections, moving pieces back and forth like some linguistic crane operator. When I can no longer stand to shave off more, I know it is as finished as it will be.