Project estimates are extremely difficult and important. Clients need ones they can rely on. They put them on their roadmaps. They make promises to their stakeholders based on the estimates. They budget according to them. There's always a pressure for the estimates to be low (cheap), yet accurate. At the same time we never have enough information about the project. This is the crux of every project. That's the intersection of plans, expectations, priorities, assumptions and uncertainties. How do you handle all that?