I have been re-reading "First Man- the life of Neil Armstrong" by James R Hansen.  The book is a gem - it so well researched and so well written.  It reminds me of my time at NASA and the key things I learnt there.

1) too long spent on design leads one to implement a dud and too little time spent on design leads one to implement a white elephant.

2) single points of failure are everywhere in large projects.

3) risk is ever present but usually hits you where you are not.

4) simulation is preparation if and only if you use it to go beyond the limits of your known systems.

5) there is no substitute for experience but experience without imagination is useless in a crisis.

6) fear of failure can not be tolerated.

7) success is filled up with good luck.