You ask about things you know will be necessary as well. In an interview the time shouldn't be spent entirely on academic programming questions. They're there only to gauge problem solving skills in real time in a stressful environment, which work sometimes is. Who says you can't fit any of the above mentioned programming problems in 10 to 15 minutes?
Wouldn’t asking real-world questions that the person will definitely run into during the job also gauge problem solving skills? Unless problem-solving isn’t part of the real job, in which case it’s not worth testing for.
If your point is that you do a mix of questions that are definitely relevant and some that are academic and might be relevant, why not just do 100% known-relevant questions? What’s the value add of asking questions that are less than 100% relevant?
