The short answer
Stop optimizing the roster and start optimizing how people talk to each other. Cross-functional teams ship well when information flows freely across roles — not just up and down the chain. Map who talks to whom, find the gaps, and close them deliberately this week.
I keep building the team right on paper, but something still breaks at ship time. Research on cross-functional product teams points to one consistent culprit: collaboration doesn't happen just because you put the right roles together. It happens when people actively share information across role lines — design to engineering, engineering to product, all of it. Communication patterns inside the team shape output more than the org chart does. A team with strong internal links ships. A team with siloed nodes stalls.
Marcus puts it plainly in Meditations 11.4: 'What is thy profession? to be good.' He's not talking about title or skill. He's talking about how you show up in relation to others — with intention, consistently. Your job as a team builder isn't to hire well once. It's to keep asking, every week, whether you are actually doing the thing that makes the team work. Are you creating the conditions for people to connect? That's the practice, not the plan.
This week, draw a simple map — on paper or a whiteboard. Put every person on the team on it. Draw a line between two people only if they talked directly this past week, not just in a group meeting. Look at who has no lines, or only one. Pick one gap and fix it: set up a 20-minute sync between those two people with a real question to answer together. Do that once, then again next week. That's the habit.