Comment by mibsl

For me, unstructured things (like non-formal diagrams, notes, pseudocode) are close to useless. I much prefer sketching the API surface in code right away and then iterating on it, building abstractions which cut the shapeless thought blob into neat, predictably interacting parts. The code is my notepad and the compiler is with me, every step of the way, catching contradictions and handwavyness.