For GRE Q, 167-168 is good enough imo. In terms of advice, when you take a GRE practice test, there should be some consistency to what you’re getting wrong. Once you fill that gap in knowledge, you should be able to do better. But if you’re not focusing on filling that gap you’ll never do better than what you’re doing now.
Another important tip, when you study for GRE on problems you struggle with, you should replicate the conditions of the exam. So, if you’re not doing well in the second Quant section, but doing perfect in the first, then you should study the questions you struggle with after work, when you’re exhausted. if you struggle in the beginning then you need to replicate the conditions of the first half the exam: when you’re theoretically mentally fresh. If you struggle with the time constraint, you should also study the exam timed, to replicate the feeling of rushing.
Hope that helps in some way. Good luck!