Which law asserts that the first 90% of a task takes 90% of the time, and the last 10% takes the other 90%?

Which law asserts that the first 90% of a task takes 90% of the time, and the last 10% takes the other 90%?

• A. Hofstadter's Law
• B. 90-90 Rule
• C. Conway's Law
• D. Putt's Law

Answer: (A)

Think about how tasks rarely chunk out evenly. The 90-90 rule captures a common pattern: the first 90 percent of a job often seems to go quickly, while the last 10 percent drags on because of debugging, integration, and polishing unseen issues. In practice, those finishing steps require a lot of careful work, fixes, and checks, so the final phase can take as long as, or longer than, everything that came before. That’s why estimates tend to look optimistic early on—the difficult finishing work dominates the total time. For context, Hofstadter's Law speaks to the general idea that things take longer than expected even when you account for that, Conway's Law connects organizational structure to design outcomes, and Putt's Law says work expands to fill the time available.

Think about how tasks rarely chunk out evenly. The 90-90 rule captures a common pattern: the first 90 percent of a job often seems to go quickly, while the last 10 percent drags on because of debugging, integration, and polishing unseen issues. In practice, those finishing steps require a lot of careful work, fixes, and checks, so the final phase can take as long as, or longer than, everything that came before. That’s why estimates tend to look optimistic early on—the difficult finishing work dominates the total time. For context, Hofstadter's Law speaks to the general idea that things take longer than expected even when you account for that, Conway's Law connects organizational structure to design outcomes, and Putt's Law says work expands to fill the time available.