>>vimes6+(OP)
Work expands to fill the time you have. If you don't set a goal, you'll never ship. Estimation is not an exact science, but, I rather set a goal post that I can move if I need to than not have one at all.
>>webarc+W5
"Parkinson's law is the adage that "work expands so as to fill the time available for its completion". It is sometimes applied to the growth of bureaucracy in an organization."