You might need to be able to do the calculations in order to pass the exam, but when flying a real aeroplane, you won't be able to to the calculations in your head, before, or during an approach.
927 fpm isn't a practical parameter, so you might ask, other than being able to pass an exam, why are you required to be able to work it out ? ( about 1000/900/800/700 fpm depending on wind direction, it could be argued, are more practical numbers to learn ?
It's a bit like being able to plot a course with a pencil and a ruler on a chart. Had to do it in order to pass an ATPL exam many years ago, but never, ever, used the ability in practice.
It might be argued that the syllabus needs an overhaul ?