The ideal purpose of a technical interview is not just to gauge whether the candidate has all the skills required for the job (this is a best case scenario that

The ideal purpose of a technical interview is not just to gauge whether the candidate has all the skills required for the job (this is a best case scenario that rarely happens), but also whether the candidate has the ability to learn the requisite skills that s/he currently lacks. If the technical questions asked during the interview are relevant to actual problems encountered on the job (unfortunately, they often aren’t), having to brush up beforehand is a good test of the candidate’s ability to apply their existing skillset to novel problems. However, many technical interviews ask algorithmic puzzle questions that are totally irrelevant to the job; having to study those (and administer those interviews) is a waste of everyone’s time. In lieu of a formal coding interview, I sometimes like to give a short 1-2 hour takehome assignment that asks the candidate to solve a simple but real problem I’ve faced on the job. The candidate’s response to this is infinitely more informative than any coding interview could be.