This.

When I hang out with other rationalists in real time, they can actually respond to and point out particular thought processes. Sometimes it's pointing out or joking about a particular bias, other times it's just waggling their eyebrow and asking if I'm sure.

The real-time feedback helps learning so much it's ridiculous. The 1 week I spent in San Francisco probably saved me a few months of time, and there are specific useful insights that I don't think I would have ever come up with on my own.