This same situation happened to me, I was PTing mid 160s and taking one PT every two days the weeks leading up to my exam. The last one I took was only 3 days before my test and the only time I scored in the 150s. It was terrifying, but I took a mental break the last two days and didnt do anything LSAT to give my head a break and I pulled the higher end of my average scores on the actual test. I recommend taking a break to give your mind a few days to rest, or at least not taking full length tests for a few days. Just go over missed questions from previous tests for a few days or do small sections. Also, the newest practice tests seemed much more difficult to me than earlier tests as the questions seem to be changing. I recommend taking the newest tests possible to have the closest idea to what the real test will be like. Good luck!