I finally did it!

I started my GMAT journey in the summer of 2019. I took a practice test and scored a 640-- I wasn't sweating it because I had been out of school for a few years and I knew I could brush up on the quant rather quickly (or so I thought). Just for reference, I have a masters degree in chemical engineering.
Kaplan
I signed up for private tutoring with Kaplan online 10 hour course. I watched some of the lessons, but quickly got bored. They were slow.. I did not feel my tutor was very helpful and about halfway through I started searching for alternatives. (I've had good luck with Kaplan for LSAT (scoring a 167) but this does not seem to be their strength).

In Person tutoring
I did two months of in-person tutoring and was able to increase from 640 practice tests to a 690 real GMAT test. I took the GMAT 3 times (690,Cancelled,690) and wasn't making much progress. I was having timing issues in the quant section (either too fast or too slow). I often panicked when I got to a quant problem that I felt I should know, but couldnt think how to solve. I was frustrated with this tutor (who also crossed some professional boundaries) because usually standardized tests are a strength of mine, but the GMAT was winning.

Manhattan Prep Advanced online course

This is where Mark comes in, after 3 attempts at the GMAT, I was willing to try something new. I signed up for the advanced online class through Manhattan prep. I typically stay away from online group study classes because it's easy for me to get distracted completely defeating the point..

Mark's advanced online class was excellent. It skips the basics and jumps right into how to increase your score. He keeps everyone engaged by "cold calling" which kept me from playing on my phone and I learned a lot from my classmates. What I learned especially on verbal was that while I may have gotten the right answer, it wasn't necessarily always for the right reasons!
I also challenged myself to make sure I did ALL the homework in between the lessons. I really enjoyed the Manhattan prep video lessons that they had on topics. I watched all of them multiple times. However, my mistake here was that I did not do all the practice tests. Therefore I still struggled with timing and test stress when I took my 4th GMAT a month after the class finished.
My score improved (finally!) to a 710 (Q44, V44). My verbal score benefited the most from the advanced online class and I went from a 40 to a 44.

Mark Sullivan Private Tutoring
I was happier with the 710, but still not satisfied. I really felt I had more I could do on the quant. I reached out to Mark to see if he was available to help me while I prep for my 5th and final GMAT about a month later. Luckily he was and we got started right away.
Working with Mark for private tutoring after the Advanced Online class was absolutely the right choice for me. I had the strong base (from doing all the homework) and I knew how he taught. We were able to build on that really quickly and I improved every tutoring session. He had me practice every day on timing and I did regular practice tests. The private tutoring was great because then we could really expand on my unique questions.

Thanks to Mark I had a 40 point improvement in my GMAT score!