If you haven't done so already, I would definitely recommend recording yourself while you take the PT's and analyzing your test taking strategies. At this point, you are not only aiming for higher accuracy but also more refined testing techniques as well. I felt that analyzing the recordings really helped me get rid of inefficient habits and develop an internal clock, and I think the confidence that followed not only improved my timing but ultimately my accuracy. I think my jump from a 166 to 171 is largely due to the recordings.

As for the retakes, I found these to be very helpful also. I think doing the tests again really makes you retrace your thought processes. To improve stamina, maybe try doing them 30 mins/section or try adding sections to take maybe 5,6 section PT. I found this to be helpful.

This link is helpful if your school is on the list

https://www.lawschool.life/forums/viewtopic.php?f=35&t=153&sid=68223b04b2a8e5a380589872b1e9e708