Screenwriter Parables by J.A.:
The Line-Painter Dilemma
A guy is hired to paint the yellow line down the middle of a country road. The first day, he paints five miles. His supervisor is impressed. The second day, he only paints two miles. His supervisor thinks, “Well, maybe he had a bad day.” But the third day, the guy only paints half a mile. The supervisor asks the guy what’s wrong — why is he getting so much less done?
“Well,” the guy says, “I have to keep walking back to the paint can.”
The screenwriting equivalent, of course, is that at the start of each day’s work, one’s instinct is to go back to page one and read-slash-revise up to where you left off. Which is a very counter-productive habit.