If your methodology/practice/bureaucracy/approach/whatsoever does not allow your people to manage what is unpredictable you are going to get lost, the bigger is the project higher will be the complexity to get out of the maze. The assumption methodology is the solution to manage everything properly is fundamentally wrong, nothing have been ever managed properly in human history, nothing is bullet proof, and in every flowchart you need a line turning all the way back home to where you started…
And… don’t miss accountability, one problem, one owner, one; only one, no matter what. Two owners = big trouble!
If your own application is not compatible with anything else than IE6 why should others be?
