Hard deadlines
A date set by someone who does not care about your sprint. Election day, a filing date, a regulator. The only real teacher of shipping I have met.
Also called immovable deadline, an immovable deadline
I ran digital operations for three national political campaigns: a Senate re-election, a presidential primary, and a general election. Political deadlines are set by law. The first Tuesday after the first Monday in November does not move because an integration is unfinished. There is no December release.
That changed my engineering instincts in a way agile ceremonies never did. I learned which part of a feature mattered and how quickly the rest could be cut. An ugly system running on election day beat an elegant one arriving afterward. Scope had to be cut early and out loud, not quietly at the end.
I have also seen the other kind of hard deadline: a ground-up rewrite driven by SEC compliance, where the date was set by a regulator and the requirements were set by construction rather than by preference.
Most software deadlines are negotiable and everyone in the room knows it. Working against a few that were not is the most useful thing that ever happened to my judgment about scope.
See also Player-coach.