An expert is the one who predicts the job will take the longest and cost the most.
Friends come and go but enemies accumulate.
Any given program will expand to fill all available memory.
Every clarification breeds new questions.
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.
Investment in reliability will increase until it exceeds the probable cause of errors, or until someone insists on getting some useful work done.