When you have a list that's longer than you can deal with, you have to prioritize," Urs instructed us. "If you give a project a quick improvement that gets you eighty percent of the way to solving the problem, you haven't solved it, but it drops below the line versus one you haven't worked on at all." And then he put his finger on the crux of my conflicts with engineering. "Once a problem falls below the line you should work on something else, even though it's not finished."
This was Google in 2000, where good enough was good enough. This quote is from page one-hundred twenty eight of Edward's I'm Feeling Lucky.