Below is my question that was closed. I feel this is a valid question for SO. This seems to be happening too frequently to questions that shouldn't be closed.
Where did the estimation rule of thumb originate that time spent will be one-third in each of the following: design, implementation, and testing? [closed] I commonly hear that one-third of a projects time will be spent in design, one-third in implementation, and one-third in testing. The three phases of development seems to be derived from the waterfall model. But, where did the time division originate (1/3, 1/3, 1/3)? Is there a paper or book that this is from?