Wing it.
I did this once actually, with my Jap 1 exam.
I had macro in the morning and Jap in the arvo on the same day, and I was in danger of failing macro because the exam was worth so much.
On the other hand, Jap written exam was only worth 40% and out of the 60% that had already been assessed, I'd gotten about 58%.
Since there was no hurdle requirement, I had passed Jap without even walking into the exam.
I planned to study briefly in the break between exams while I ate my lunch, but I grew ill and had sharp pains in my stomach (in hindsight, the ham I had in my sandwich for breakfast probably wasn't as fresh as it should have been). I had neurofen with me, and it kicked in in time for my Jap exam, but I hadn't studied.
I ended up getting about 94% for the exam, and an overall 95% unit result.