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.
"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."
The problem is that negotiations phase where the devs get screwed down on the “price”. This is of course a silly thing for management to do given they are paying by the hour anyway!
