If I were to get a "coding assignment", I would tell them 'no'

So I would spend 0 minutes

And not just because I am not especially close to a 'coding' or 'developer' role in my IT career

But because they are all* a complete and utter waste of time

Unless you mean a whiteboarding session in an in-person interview, where you see approaches to problem solving, swags in the direction of an answer, refinement of the problem statement, etc - those I spend 15-20m on (out of the 45-60m interview session)

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* maybe there is a coding assignment that is not a waste of time, but I have never in my well over 20 years in IT seen it