I suppose that could happen in the best circumstance. But in my experience, there are two things wrong with the "here's a problem I solved last week" question:

I suppose that could happen in the best circumstance. But in my experience, there are two things wrong with the "here's a problem I solved last week" question: - the scenario is way too specific. Say you have some unusually pathological database that was developed in house, and you need to query it using a proprietary wire format that only your company uses. And you discover some kind of trick that sort of works. This is a TERRIBLE question to ask a candidate, but I've seen it done. The candidate is fighting in the dark, trying to grasp the outlines of the problem, for the full ten minutes. - asking about stuff you did last week leads to the interviewer comparing themselves with the interviewee. A fair-minded person can see there might be other approaches. Most people are proud of their own solutions though, and won't accept alternative answers. It's better, psychologically, to use a problem you aren't personally invested in.