What principle suggests that adding more people to a project can actually increase completion time?

The principle that indicates adding more people to a project can actually increase completion time is Brooks' Law. This concept arises from observations made by Fred Brooks, who noted that in software development projects, bringing additional team members onto a late project invariably leads to further delays rather than accelerating progress.

This occurs for several reasons: first, newly added members require time to get up to speed on the project, leading to inefficiencies. Additionally, existing team members may need to divert their focus from productive work to assist newcomers, which can disrupt workflow and communication. The complexity of coordinating larger teams also increases, often resulting in misunderstandings, conflicting schedules, and complications in task assignment that can impede rather than enhance productivity.

This principle serves as a critical reminder in project management, particularly in software development and similar fields, highlighting the importance of efficient team dynamics over mere numerical strength.