Do you try to explain the lack of a third night by saying that the Messiah was using common figure of speech?
From what I read in the commentary it sounds more like a difference in viewpoint or way of looking at things. People back 2000 years ago weren't concerned as much about whether 3 days was exactly 72 hours.
In the Matthew account at 27:63 the Pharisees understood Jesus to mean that "after three days I will rise again." According to that passage they didn't seem confused about what he meant.
Another factor to consider is that the particular words chosen may have been used to create some sense of parallel with the LXX account of Jonah. So, in a sense, Jesus (or Matthew) may have taken some 'poetic license.' The people listening to him did not have a brochure of what he said to take home with them. But they were likely familiar with the Jonah account from Scripture readings in the synagogue. So, choosing words that would stick, although not technically accurate to a "pedantic Western" viewpoint, may have been the way to go. I'm sure many modern speakers use similar strategies to make their point memorable.