The artist who aims for perfection in everything achieves it in nothing.
There were several pages in the sketchbook this week that had minute beginnings of drawings that were stymied in the early stages. A good answer to this problem is to use the page as a doodle dump, adding and overlapping elements over time in an organic way. Aim to complete something on the page. It is a good image-making exercise, and perhaps results in something more interesting than the original goal. If not? Who cares? At least paper was not wasted or torn out of the sketchbook.