If your score is fluctuating that much, it's likely that there are inconsistencies in your process. This could be because there are holes in your content knowledge (forgetting geometry rules, or relying on your ear too much in SC). Or - and perhaps more likely - it could be due to careless errors. Careless errors are the #1 cause of score drops on the GMAT, but most students tend to overlook them.

It's important to track patterns of errors that you make on practice tests or on OG problems. Once you've identified the errors, you can think about ways to fix them:
- if you skip steps in algebra, you can fix this by writing down every step
- if you misread the question or answer the wrong question, take a moment to re-read the question before locking in your answer
- if you get the questions and statements mixed up in DS, find an organizational system that you can stick to
etc.

Here is an article about how to track your errors: https://www.manhattangmat.com/blog/index ... -studying/

When you're reviewing practice tests or practice problems (which you should always do for every problem, right or wrong), hold onto your notes (if you took any). For RC, ask yourself - did I miss this question because I misread/misunderstood the passage? Because I misunderstood the question? Or because I jumped to conclusions in the answer choices?

Here are some strategies to help with that:
https://www.manhattangmat.com/blog/index ... rehension/
https://www.manhattangmat.com/articles/come-again.cfm