If you have a management team that is very weak when it comes to planning agile does help a lot allowing the world of actual work estimates to enter the equation, or in the sprint structure you can broach the question 'what gets bumped to do this?' If a management team has an endless leash they just stack a thousand different arbitrary pieces in a pile, call it a release and set a deadline. Using agile enforces a workflow for short term planning where one didn't exist.
