Hello everyone!

So I've taken three prep tests -- two I did all four sections and another I just did 3/4 sections. My current scores have been 141 (all four sections), 148 (all four sections), and 145 (three sections). I've noticed that on all three tests I get the lower difficulty questions right but I miss most if not all the harder difficulty questions. So I'm not sure how I should approach my studying. Should I just drill non-stop the harder difficulty questions? Should I prioritize the question types I get wrong most often according to the PrepTest analytics? Any advice would be very much appreciated!