A common reason for disagreements is differing definitions. I once had a discussion with a friend about egoism and people’s ability to do truly altruistic acts. After an hour though, we suddenly couldn’t agree more. That was when we decided to define egoism.
Defining what done means is essential of exactly this reason. If you don't know what people mean by "done", how do you have meaningful conversations about progress and the state of work? How can you be confident when asking for estimates?
