Crunch is rarely a necessity. If the deadline can't be moved, and you're going to miss it, work on cutting the workload (drop features, etc...). If the project can't have any corners cut, then move the deadline. If neither of these is an option, then do what you have to do and find new managers for the next project, because they should've been more on the ball and planned for potential slippage by giving a time buffer to avoid crunch.