My interviews are conversations to get to know you, your background, your professional interests, how you think about problems and how closely your resume lines up with those conversations. I like to get people talking about their work to see where their energy level goes.
When we start talking through a hypothetical data problem there are people who will describe the problem from the UX perspective, the app code perspective and the database perspective. The question prompts that portion of the conversation.
Precisely. And why not? I have my fellow developers do that ( ask trivia and label the interviewee incompetent, if he cannot answer it) , and most people who have reacted to your post have also probably seen that.
Anyway humor me and tell me how much time it would take?
Using the concepts in how you naturally think about problems?
That will only come from experience. I can't say exactly how much but I'd imagine something in the realm of 6 months minimum of applied usage to different problems.
(+) average= meaning the programmer should be able to say 'solve' the FizzBuzz under comfortable conditions. Or say add the first n items in an integer array etc...