This post has very little to do with deadlines and a lot to do with describing the behavior that sets apart senior engineers from junior engineers, in my opinion.
Dan argues that any definitive answer to the question: “can your team get spec X done in Y months?” is the wrong answer. The path to the right answer has to start by responding with a question of you own: “Why?”. This is an over-simplification, of course.
What Dan is really advocating for, is to start by developing a good enough understanding of the underlying business problem that led to the request in the first place. Then, we have enough business context to figure out what work we really need to do in order to address it. And finally, we can present a realistic plan that takes uncertainty into account.
Trying to summarize Dan’s post in a single paragraph really doesn’t do it justice. Reading his entire post WILL be a good use of your time.