2nd attempt w better prep but score drop from 700 to 670

Hello guys! I have been a long time lurker but my attempt at the GMAT yesterday ultimately made me sign up here as I would like to get some advice from you guys on how to proceed with my GMAT prep regarding a prospective third retake.

I took my first GMAT three years ago but I did not take prep too seriously by then. I only needed to get into a European MIM programme and any 600+ score would suffice, so my aspirations were not necessarily that high. All I really did for prep was to work through the OG. In so doing I figured that Verbal did not really pose any significant difficulties to me. Math was a different story though. I never took math too seriously in high school and for the most part it wasn't really one of my strongpoints. So I purchased the Manhattan Guides and worked through them. By the end I was by no means an expert in math but I had functional basics with which I took my first GMAT. The test was a dreadful experience as I hadn't sufficiently practiced CATs before and I constantly fell behind timing in Quant, leading me to guess almost every second question. Verbal was the opposite, I breezed through that section with about 15 min to spare. Ultimately I ended up on a V42/Q44 combined 700 with which I was happy for the time being.

Now I am applying for a PhD and decided it might be a good idea to improve my score a bit. I worked a lot with numbers lately and I felt that my numerical abilities had improved by quite a margin. So I decided to give the GMAT another shot. I worked through the OG again and, indeed, the math came a lot easier to me, although I still struggle with some of the Algebra / Number Properties stuff. Verbal again wasn't an issue to me, so I largely ignored it on my prep. I also purchsed the GMAT Prep package to improve my test taking abilities, as I didn't want to get into the type of timing troubles as I did last time. On all 6 GMAT Prep CATs I ranged between 730 and 760 now with Quant hovering around the 70th %ile and Verbal fairly stable between 97th and 99th %ile. So I felt ready to improve my GMAT score.

On the test day I didn't have any significant time struggles during Quant, but I skipped some questions that were in my weakness areas and of which I knew I would have most likely gotten them wrong anyways. However, at some point the GMAT was throwing some really simple questions at me that I would expect to see in the first quarter of the OG, so I began to grow a bit worried. But all in all, I skipped less questions than last time and was way less stressed out upon finishing Quant.

The Verbal section was much tougher though than anything I had experienced before. While usually I would just be able to "see through" the questions, that wasn't the case this time. The whole section felt "off" for some reason and I wasn't really able to get into my "zone". Some of the RCs were just brutal. While in the CATs RC would usually refer to some specific aspect of the text, I had a lot of questions that required me to "read between the lines" and interpret the text. So for the first time ever I actually came into timing troubles on the Verbal part. Before I sat the test I had taken the free Kaplan CAT. And on my real GMAT the Verbal was more similar to that of the Kaplan CAT than to that of the GMAT Prep CATs in terms of the phrasing of CR questions, types of RC passages etc. Have any recent adjustments been made to the Verbal section, that could explain why it felt so "different" to me?

Eventually, I ended up with a score of 85th %ile on Verbal and 54th %ile on Quant, Total 670, which I cancelled immediately. I was seriously frustrated. I realistically aimed for the 720 to 730 range and didn't expect that my performance would fall even below what I had scored before. All the improvements I had made in Quant were seemingly for nothing and Verbal way worse than anything had scored before. Yet, I was less stressed out during the test than before and I struggle to understand what had happened. I don't want to back down now, so I scheduled another GMAT one month from now, as I know I can do better.

The question is, where should I focus my prep now? For sure I will work on the Quant parts I have been struggling with. But I also did that before, seemingly to no effect. For Verbal I have no idea - I feel that actually "learning" the stuff would potentially make me overthink Verbal, even further lowering my performance... I would be happy for any suggestions on what might have gone wrong on test day and how I could remedy that on my next attempt?