Hi whatsinthename11.
First, if I have it right, within Q51, there is a bit of a range. I mean, Q51 scored with 36 questions right is not the same as Q51 scored with 34 questions right. So it may be that to get 20 more points by going from Q50 to Q51, you have to go from a lower end Q50 to a higher end Q51. I don't know that to be the case, but I suspect that it is.
Having said that, regarding, GMAT Club Tests, you can definitely learn from them and build some confidence from using them. The questions are so hard that they make the questions on the actual GMAT seem easy. Also, I found that when I used the GMAT Club tests I got much better at handling the pressure of quant. I had to just keep seeking to get right answers, even though sometimes my getting a high score seemed unlikely.
I don't know anything about the eGMAT Math Scholinarium.
Having said that, I can tell you this. If your quant score is not what you want it to be, there are aspects of quant that you could be better at handling. What you really need to do is to figure out what those aspects are and address them directly.
One way to do that is the following.
Go to
https://bellcurves.com and set up a free practice account. In the quant portion of the question bank there are thousand of questions in dozens of categories. Go through those categories and figure out which ones you are not comfortable with, and then slowly and carefully do dozens of questions in each of those categories, seeking to achieve a hit rate above 80 - 85%. As you become more confident in finding answers to questions in your less strong categories, speed up. Some of the questions have issues, and the combinatorics explanations don't really make sense, but overall, if you can get say 82%+ of the questions right in every category in that bank, you are likely to score Q51.
You might be surprised by what you have to work on. In my case, exponents and fractions, relatively simple stuff, were giving me trouble, and some types of questions that I usually got right, such as overlapping sets, were taking too much time, because I had not worked on them much. Obviously, you can figure some of this out by going over your practice tests.
Also, improving overall accuracy can be a way to increase your quant score.
Meanwhile, another 5 points in verbal would drive your score up even more than one last point in quant. So maybe you should work on verbal. Even the upper 40's are not out of reach, even to not non native speakers of English. So maybe by changing the way you are training for verbal you could without too much trouble push your verbal score to a not so crazy upper 30's to lower 40's level.
Here are a couple of posts I wrote on increasing one's verbal score.
https://www.beatthegmat.com/help-verbal- ... tml#770848
https://www.beatthegmat.com/how-do-i-mas ... tml#762120
