[funkymike]

I think a large part of this topic isn't about a team making a promise and not living up to it. It's about a business (management) wanting to make a promise and getting the team to accept responsibility for it. So let's assume the estimate is very accurate but the business wants it done in half the time. When the project runs past that date being able to point to a very accurate estimate and say I told you so isn't very productive. So we need strategies and techniques for dealing with the mismatch between the desires of the business and what can actually be delivered in a given amount of time.

TFA advocates for bargaining on scope, where I prefer to start the conversation by asking about both scope and timelines to understand which parts of the overall request are negotiable. This is also a great opportunity to make sure the business context is well understood so everyone understands what success means from the perspective of the business

You might then find every single feature really is necessary and the timeline can be relaxed. Audit compliance can be an example when it is something new to an org. You are either going to pass or fail the audit, so there isn't really room to reduce scope. But you may be able to negotiate on the timeline.