<i>The cost of shipping the wrong thing is much higher than the cost of slipping arbitrary deadlines to ship the right thing.</i><p>That assumes you can tell what the wrong thing is before you ship e.g. without feedback. I don&#x27;t believe you can. Agile is the process we use if we don&#x27;t know what that &#x27;right thing&#x27; is. It&#x27;s better to ship the wrong thing and then fix it than to spend additional time on what you believe is the right thing only to find that it was actually the wrong thing and have to fix it anyway.<p>If you know <i>absolutely</i> what the problem is, what the best solution is, and the situation isn&#x27;t going to change during the course of the project, then even waterfall will work. Agile is being willing to say &quot;I don&#x27;t know what the solution is&quot; when faced with something and not being stopped by that problem - do what you can, put it in front of a user, gather feedback, and repeat.