Hofstadter's Law

The joke in the quote is also the engineering truth: at every level of the work, estimates quietly assume everything goes well. Engineers estimate the happy path. Product forgets how long edge cases take to discover. Nobody estimates integration testing. And two weeks before the deadline, a launch-readiness checklist appears with items nobody had thought about.

A project that feels 'almost done' is usually closer to 40% done — because 'done' also includes the part where QA finds the bugs, security raises questions about the threat model, and legal wants to review the privacy notice.

Padding your estimate by 2× is the floor, not the ceiling. The PMs who consistently ship on time are the ones who've accepted this as reality instead of fighting it every quarter.

A KYC refresh project is scoped. Engineering says 'two sprints to build the new flow'.

— The junior PM promises the stakeholder six weeks.
— The senior PM adds a sprint for translation, legal review, and edge cases they haven't found yet.
— The grizzled PM adds two sprints, pre-books the launch-readiness review, drafts the slippage comms, and tells the stakeholder 'twelve weeks, with a checkpoint at eight where we'll know if we're going to hit.'

The project ships in week 13. The junior PM is explaining themselves. The grizzled PM is on time within tolerance and already planning the next one.