Let's say you have a project with 9 parts. Each part will take ~9 months to complete. If you take 9 people and give them each one part it will take ~9 months t

Let's say you have a project with 9 parts. Each part will take ~9 months to complete. If you take 9 people and give them each one part it will take ~9 months to complete. If you take one person it will take ~81 months as they need to finish each part before they can go onto the next one.