The use of "reflect on" doesn't work here, in my opinion. The use of "direct proportion" is fine, but I reject your premise, having been involved in a lot of shift work. ) Also, when B follows A in time, it's more natural to say that B is in direct proportion to A, not vice versa.
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alc24The work that has to be done during the day reflects on the work that has to be done at night.In some specific situations, I suppose you might say, "The work to be done during the day reflects [on] the work that has been done on/during the previous night." (or vice versa)