Strongly recommend GMATWhiz, and special thanks to Piyush!

Would make the product better:

There aren't many things I'd recommend to improve, although I think sometimes the in-house quant questions veer too far into mathematical complexity and less in the pure logic / problem solving the GMAT attempts to test.

That said, even this is still helpful, as the better you understand the underlying math, the more patterns you're able to identify and more tools you have available to approach PS questions in Quant and DS questions in DI.

I turned to GMATWhiz after using another service that, despite being highly rated on GMATClub, left my quant skills lacking and shaky even after a few months of diligent preparation, and I'm so glad I did.

Piyush, the founder and quant instructor at GMATWhiz, is an extremely thoughtful and deliberate teacher. I opted for the online course along with live instruction from Piyush, and found the entire program to be highly effective.

The online course at GMATWhiz is split into modules which include video lessons and problem sets that cover each of the relevant concepts found on the GMAT. The sessions I had with Piyush would supplement this video instruction, address any doubts I had from the coursework, and involved Piyush presenting various different and time-solving approaches which helped me effectively tackle a range of question types.

What most stood out, though, was the thoughtfulness and involvement Piyush showed in my GMAT journey. As much as he helped with the course content, he also served as a mentor who strengthened my overall test approach and thought process. While the video lessons were thorough deep-dives into the quant material, sessions with Piyush helped uncover and refine my own approach, through exercises he'd create to highlight and correct any gaps in my methods, and even call out any self-doubt I was needlessly exhibiting. He'd spend time—including his own time, outside of our classes—to explain why I should approach some questions with patience, not overthink certain things, and answer any questions I had.

I strongly recommend GMATWhiz and working with Piyush. He's an extremely thoughtful instructor who goes the extra mile, meets you at your level, and helps you perform your best.