You might want to change the example to disinclude definitives and a specified day, because as things are I doubt anybody would really parse "a twenty four-hour shift tonight" as meaning that your shift would take 80 hours. There are not even that many hours in a whole day (including daytime and nighttime), and a problem that is common to all three examples is that there are certainly not 24 hours in a single night. If you don't want to change the example, because you want a definitive answer congruent with the source, I would recommend sharing the source. — Tonepoet 1 min ago