Could memorizing GregMat Vocab Groups 1-28 be enough vocab. for a V165+?

Context:

I am 80% done with the Overwhelmed Plan for Quant and 70-80% done with the 1-Month plan for Verbal. I have memorized around 15 groups so far. I am planning to give a GRE attempt by end of this month. I can probably memorize groups 1-28 with a 90% accuracy, but if I try to do all the 34 Groups, the accuracy might reduce significantly (like 70%).