Accuracy and consistency should be your main priority. Work on speed once you’ve mastered these first.
I would say 10 lines with 0 errors is significantly better than 15 lines with 5 errors. (Funny enough, I was getting 10-11 lines down with no more than 1 error when practicing, and passed to my TOC’s Enhanced standard on the day)
For consistency, you should get to roughly the same point on every sheet you complete and avoid appearing to get ‘better’ or ‘worse’ as the test goes on.
Also, if you’re not doing so already, remember to practice using paper printouts, to better simulate the test on the day.