Hi guys.
I scored a mere 680 after 4 months. There are probably maaaany people who managed to get past 700 in one month, but I started from the bottom (400).
I am writing to inform people who scored low on their diagnostic test that they
can score high.
I've been working within the M&A industry, which means insane working hours, during my whole GMAT journey. First month of my study journey had been intense, but then big projects appeared and I couldn't study much. Since the October, I could barely study at all. AND I DIDN'T STUDY BETWEEN MY 1ST AND 2ND ATTEMPT
(I only did few GMATclub tests) but this probably isn't something I would recommend you to do unless you are sure you are prepared more than enough to get the score you need.
Here's my breakdown.
21/07/2018 - GMATprep - 400 (Q26, V20)
28/07/2018 - GMATprep 2 - 550 (Q42, V23)
...some unrealistic CATs... (either not timed or solved with external sources of knowledge)
28/10/2018 - GMATprep - 690 (I don't remember the breakdown though) - I remembered few questions so the score was inflated.
I couldn't get rid of silly mistakes no matter how many practice questions I solved.
But then I focused as hard as I only could and.. first 700 appeared.
01/11/2018 - GMAT PREP exam 3 - 710 (Q50, V35)
03/11/2018 - GMAT PREP exam 4 - 710 (Q50 V35)
05/11/2018 - REAL GMAT -
570 (Q41, V28)
I thought the lack of sleep could have been responsible for that disaster but...
20/11/2018 - GMAT PREP Exam 5 - 700 (Q49, V36)
24/11/2018 - GMAT PREP Exam 6 - 690 (Q49, V34)
26/11/2018 - REAL GMAT - 680 (Q50, V32)
Now, I think I didn't sleep today (I might have fallen asleep for an hour or two). I felt terrible. But I sat the exam... quant? easy.. and then Verbal begins... 10 minutes later another test-taker enters the center and takes his seat. What was weird that he was talking to himself. I couldn't focus and I had to re-read everything twice or even thrice. I even hit the table but it didn't work, he was still talking to himself. I was about to stand up and tell him to shut his mouth up. But then I saw the 680 and I forgot how angry I had been

. 680 is sufficient for my 1st choice school!
Materials used to study:
Sentence Correction - Manhattan
Critical Reasoning - PowerScore Bible (THE BEST BOOK FOR CR, IMO)
Quant:
I read Manhattan book and gmatclub quant book once. I was doing hundreds of questions from GMATClub forum (I didn't pay attention to the source until recently).
I've gotten through a comprehensive set of official questions gathered by one of the gmatclub members (I can't remember the thread, though

). I also did many gmatclub quant tests (they are brilliant).
I hope to have helped the incoming gmat assasins who struggle with their low diagnostic score. I'll stay there for one more day in case someone asks me a question.
Thanks to all the people who devoted their time to tell me some kind words throughout my journey.
I may be back for a 720+ in a few years.