You would design an app without docs in 30 minutes as step 1 of the process. On the job, of course, you'd then expand on it with reference to docs and such. But

You would design an app without docs in 30 minutes as step 1 of the process. On the job, of course, you'd then expand on it with reference to docs and such. But everyone I know who's good at designing systems starts with a basic from-first-principles draft, and I expect any senior engineer I work with to be able to discuss one.