Humans develop, design, and build your projects. When they are aligned and pulling in the same direction, with a sense of personal ownership, that is when amazing results are possible. When they are focused on defending their turf, protecting their margins, and pushing off risk, small changes become difficult and difficult conflicts become catastrophic.
As a project leader, your responsibility is to equip your crews, to provide them the resources and guidance that will enable them to deliver effectively. Smoothness, momentum and predictability are reliable gauges of how well they are delivering. But how often have teams started a project with the best of intentions only to find the “honeymoon” was over at the first major issue. You are responsible for your team and their results, however you cannot control your counterparts. And it takes teamwork for a team to work.