Here's a thought. I prefer that the test keep giving me all types of problems at a higher difficulty level.
Assuming that the first ten matter more and I am able to squeek out the majority of the correct, and also assuming that this continues to kick out harder questions, I am still relatively likely to do OK on the remainder of the test because of the following reasons.
I as well as many other test takers eventually get over nerves and calm down after getting in somewhat of a groove in the test. My focus should increase over the remainder of the section unless I am stumped over and over and start to panic.
Secondly, there are likely to be a decent amount of difficult questions that an avg test taker can answer correctly because everyone has their strong areas. For instance, I'm likely to get most VIC questions wrong regardless of difficulty level. However, I am very strong at other areas even in the higher difficulty questions.
On top of that, I can answer a some difficult questions rather quickly, which would allow me to recoup some lost time from spending a lot on the first ten.
Whatever the case, I'd rather rush in the end knowing that at least up to a certain point I feel good, rather than prematurely rush the problems when I have 75 mins to go, only to find out that I have 10 minutes left to answer the last two questions correct (which likely won't take 5 mins per since I probably got the test to think I can't handle really difficult questions).