One of the keys to his teams' successes, as part of the whole "we work hard at working together" mantra, was to put people side by side. The user, the contracting officer, the engineer, the money person, the inspector... bring all these people into a common area, let them get to know each other and work together, and you'll find that they can get stuff done faster, cheaper, simpler (hey, where have I heard that before?).
That's one of the real benefits of the FIST approach, is that it makes proximity possible. When you've got a huge team, scattered across the country, it's virtually impossible to get everyone into the same room at the same time. But when you've got a small, co-located team, I've found that communication gets clearer & more reliable. There's more trust and respect. More willingness to help and compromise. There's better understanding and a greater sense of belonging.
These things all matter tremendously for system development projects, even though they're not taught in engineering schools.
One more time: proximity matters.