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In a highly competitive job market you'd be wise to go into the interview well-prepared.
If you're already in a job you might want to do this quiz for the fun of it. Or as a semi-serious self-appraisal.
Every professional has a breadth of knowledge and a depth of knowledge. It would be fair to say you can't have depth in everything, but it is definitely massively useful to have some depth across a broad range.
It is important to have total mastery in the area in which you wish to work, because there is no such thing as a job for life; not anymore. The more you know, and the more you can do, the longer you'll survive.
