Hello.
I scored 161 in Quant in PP1, and, after about 1.5 months of learning Quant strategies (like choosing numbers, back-solving etc.), scored 159 in PP2 
My low score was due mostly to careless mistakes.
In addition to cultivating habits to avoid careless mistakes, I am currently focusing on doing some harder Quant questions from GMAT OG and Greg’s Question Bank under timed conditions.
My question is, when would I know that I am almost ready for a 165+? For example, if I randomly choose 20 questions from GMAT OG to do in 40 minutes, how many of them should I get correct?