The collocation is 'spare no effort', but sounds very odd in conjunction with 'spare the time'. So in this context it'd be better to say 'for spending the time and effort' or use two different verbs - 'for taking the time and sparing no effort'.
Good question though. 'Sparing the time and no effort' comes quite close to Syllepsis - Wikipedia, the free encyclopedia , but I don't think it is, quite, as the verb doesn't change meaning with respect to its two objects; but as the first object is literal ('spare time') and the second is figurative and hyperbolic ('spare no effort') the two objects don't sit comfortably together. (That's my view anyway, I think. Maybe other teachers disagree... )
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