Consider timezones: engineers in Madrid and engineers in San Francisco had almost no overlap in their working hours. Good asynchronous communication was essential.

Over time, I noticed that the teams that were most effective at this scale were the teams that had a strong culture of documentation and automated testing.

As I started to work on my own array of smaller personal projects, I found that the same discipline that worked for large teams somehow sped me up, when intuitively I would have expected it to slow me down.