I'll also wholeheartedly agree with this comment—my company has a long history of shipping on time and under budget. The caveat is that we closely follow #2: we

I'll also wholeheartedly agree with this comment—my company has a long history of shipping on time and under budget. The caveat is that we closely follow #2: we aggressively strike requirements from the overall target if it means preserving the integrity of the project overall, with a commitment to return later. I'll add this: a product team that ships earns 1) more credibility, and 2) that credibility is reciprocated towards the team in the form of greater flexibility and freedom to set their own targets.