I have taken 6 mocks out of 15.
My scores are 720, 730, 690, 760, 740, 710
I believe I am eligible to answer your question, but I am only talking about my experience; I am no expert, so please don't trust me blindly.
Mock tests are an essential part of any successful GMAT strategy, hence you must do your own research.
Pros:
- Value for money
- GMAT-like user experience
- Great post-test analysis
- Probably the closest to the real thing
Cons:
- The test is not adaptive
- Both the sections are a bit lengthy (But I am not complaining)
Conclusion:
15 tests are enough to build stamina for the D-day. 4000 is not a lot, so why not?
I have a question (would want experts to express their views):
I am only relying on these mocks now, as I have already exhausted the official mocks. But that was last year, and I couldn't take the GMAT because of some family issues.
How reliable are the scores? Do they reflect my actual preparation level? @
Experts' Global