Each line of snow I pushed my shovel through was a character's plot line. One line blissfully traveled across the cement. A second line ran parallel then veered off. A third line ended abruptly. A fourth line crashed into several other lines as it plowed across. And so on.
No line was perfect. Many lines left snow behind.
Messy plot lines are far more interesting to read. They keep readers curious and involved in the story.
Messy lines are also more fun to shovel.