A lot of cheating is about time not difficulty. Rather than spend several evenings practising they partied instead, perhaps justifying cheating by deeming the exam topic an irrelevance.

One of the takeaways here should be for the exam setters. If cheating was widespread (it sounds like a one off here) then they should consider whether the exam itself was an appropriate task, or whether there was an alternative task that may have been more engaging and ultimately a better test for all.