The Ninety-Ninety Rule of Project Schedules - the first…
“The Ninety-Ninety Rule of Project Schedules - the first ninety percent of the task takes ninety percent of the time, and the last ten percent takes the other ninety percent.”
About This Quote
This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation.
Most projects spend the bulk of time on early tasks, while the final phase often consumes disproportionate effort due to unforeseen complexities.
In simple terms: Early work dominates schedule; final work is unexpectedly hard.
Key Takeaway
Plan extra time for the final phase.
Themes
project management
time estimation
efficiency
planning
Mood
pragmatic
analytical
cautious
Type
practical
advisory
When to use this quote
- software development
- construction
- event planning
- research projects
Key Concepts
risk management
schedule compression
resource allocation
Questions to Reflect On
- How can you identify hidden delays early?
- What buffers can you add to the final stage?
A Different Perspective
The rule may not apply to highly iterative or agile processes where work is evenly distributed.