- over time. Lots of PMs freak out when their first sizing meeting runs over an hour. An hour! Wow!
- Estimate From the Outside In - Finally, another tip from psychology: studies have shown that people estimate projects better if you ask them how long it would take some other team to do the work instead of their team. . That means the final, critical step is to take all of the information you've gathered in estimating and then "step outside the team" to pick your sizes.
Good teams talk a lot about what's going on in their project. They know that communication is the number one problem all teams face. We have a lot of stuff we need to do in a project, like tell folks when things are going to be completed, get feedback from users, or agree on design principles. As we go about doing these things, we use exercises to help us along. But we make a mistake if we confuse the exercise with the larger purpose of the project. You can be in a sizing discussion and segue off into a design talk -- that's perfectly fine if it's required for sizing. If the team is talking about big things first, and getting resolution on these big issues, then the "craziness" of having teams spin off like this will dissipate over time. If you're not doing these things, then it's time to start.