Covering every square millimeter of space inside the insect is not important. The flecks of white paper showing in the body of the insect give the appearance of reflecting light. With these white flecks the insect will appear alive and, if we are lucky, in motion. If the insect is worked too much or ruler-like lines are applied too carefully, the quality of life will be lost. This is one of the elements in which the art of the East has much to teach us.
Much practice is given to the perfection of the spontaneous and irregular line.
The linear brush stroke, called sembyo, used on the wings, legs, and other markings, is truly calligraphic. Whether or not it is spontaneous is a matter of debate among non-painters. One must trust the line to be what it 'needs' to be. After a while painting, a rhythm develops. So, to a degree, it is spontaneous.