"First, writing the decisions down is essential. Only when one writes do the gaps appear and the inconsistencies protrude. The act of writing turns out to require hundreds of mini-decisions and it is the existence of these that distinguishes clear, exact policies from fuzzy ones."
The Mythical Man Month, Frederick P Brooks Jr.
In writing a project plan, decisions have to be taken. What deliverables are to be completed? What are the activities needed for each deliverable? Some activities cannot take place until others are completed: link the predecessors, the successors. Who will need to be involved? Will they be available? Do they want to be involved? Is there sufficient elapsed time to consider, to reflect, to think through? Have holidays been taken into account? Did we take into account business as usual considerations?
The project manager prepares a plan based on hundreds of mini-decisions. Clarity is brought where before it was unclear. Those reviewing the plan should not under-estimate the challenge to prepare such as document. In thinking this through the gaps in previous assumptions will appear. Each one takes time to be considered and to be resolved.
As the saying goes ‘The devil is in the detail’