> You won't get competence in managing the budgeting, planning, and execution of a subway line without doing it a lot.

> So how do you break the cycle of inefficiencies leading to people scared to start enough projects necessary to build expertise?

I wonder if this could be something that's only possible when you're riding on fast exponential growth - fast enough that you can afford starting more and larger projects faster than population growth (or at least faster than competent people entering management work), with confidence that this "spending spree" is self-sustaining. Once you lose that confidence, you start worrying, lose velocity, and then lose capability.

This would explain why it seems that nations tend to rapidly industrialize and improve across the board, in a kind of push that lasts for couple decades, and then runs out of fuel, leaving the nation barely able to do any large project anymore.

An analogy in my mind is to a scramjet: an engine that allows you to achieve extremely high velocities, but which itself needs you moving very fast to even start it - and conversely, if you let your airspeed drop past the threshold, it will stop working.