[Cederfjard]

Estimates aren’t necessarily accurate just because they end up being close to reality - that could just be chance. The estimate for a project that came in substantially under budget was just as wrong as one that came in substantially over, it’s just easier to live with. If all estimates are wild-ass guesses, then some will come in on time and budget, some will undershoot and some will overshoot.

I do believe that estimates, even for complex projects, are useful and can be fairly accurate, and in a lot of circumstances they can be used as the basis for deadlines, with certain considerations.

[Frost1x]

If "achieving" your estimate included a lot of crunch, your estimate was bad. A lot of poor estimation externalizes it's error to those trying to meet the estimate. Long hours, weekends, etc. over months while pretending the work fit on a nice paced 40 hour week with breaks is not a good estimate. Chances are, there's probably a lot of corner cutting in the final product as well, because your requirement set and associated deadline was the priority vs having a quality product delivered.