I agree about #3, Mike. Then the negotiations and conflicts begin, which also chew up valuable time.

Like you say, big cross-functional projects get done when higher ups put a priority in writing, give it a deadline and distribute the priority to all key players. Those projects need an executive with the power and authority to instill discipline.

I also agree that low priorities never seem to get done. Frankly, I think they are good to put on a list mainly to force people to commit to higher priorities and not just make everything a priority.