Thrash early to ship projects on time

Most important projects fail because Very Important People in your organization decide to make a last minute change.  The closer you get to ship time, the more changes from the top you will get.  Their ideas are usually great, but you would have liked them on Day 5 of the project, not midnight before the proposal is due.  Get your organization to thrash early by having everyone to agree to no changes after Day 5 (or 10, whatever makes sense).  While the new ideas may be good, they will remain only good ideas because the cost of incorporating them at the last minute is losing your bid and opportunity to get an exciting project out the door so you can move on to the next.