sure that is what you want."
If you want to make sure you never get into a position like this, build a prioritized list of features. And, move to time boxed iterations, making sure to implement by feature and always having releasable software at the end of each iteration. Management can always re-rank the list of features--and it's very clear that to add something for the next iteration, some other feature has to come off the list.
If you can release on a short cycle, you can get management to stop asking for additional features late in the game. And you don't have to say yes even when it's impossible. You break the downward spiral with frequent releases.
If your customers don't want frequent releases, that's OK. Not all your customers need to take every release. Sometimes your customers are testers; sometimes they're senior management. Sometimes they're people who use the system every day. But part of what breaks the codependency and the spiral is being able to see the new features working.
The Key to Winning
Attempting to jam more features into a release adds technical debt and may cause a delay in the release--yet teams everywhere try to do so. If you're deep into the downward spiral, move to time boxed iterations, finishing feature by feature. Work with your management or marketing to decide when you can release. Keep a rank-ordered list of features to add, and add them in time boxed iterations in that order. It's the ability to change the rank ordering between iterations, coupled with short iterations that takes the immediate pressure off and breaks the spiral.
Saying "We gotta have it" and "We can't say no" allows managers and project teams to blame each other for not knowing which features are most important and not implementing by feature. You don't have to play those games. Ask questions and organize the work so that you are able to release at frequent intervals. That will stop the codependent schedule games and provide a product to your customers faster.
I thank Dave Smith and Dwayne Phillips for their review.