Firstly, it is not the quantity of questions but the quality of questions that matters.
A good quality question is one that teaches you something new.
Which is why it is very important to do the following:
1. When you read a question, ask yourself - "How is this one different from all the other questions that I have done?'
Watch our for tiny variations.
2. Then ask yourself - "Can I clearly identify the known and the unknown?"
3. The next question is - "Do I have the information to go from the known to the unknown?"
4. After solving the question, check the explanations given and see whether your answer is right or wrong.
5. If your answer is correct, check why the answer is correct according to the author of the question and see whether your reasoning agrees with the author's.
6. If your answer is incorrect, check why the answer is incorrect according to the author and see how your reasoning differed from the author's.
7. Check each option to understand why the wrong options are wrong and why the right answer is right.
8. Note down new concepts that you learned from doing this question.
9. Check if you can explain the question if a ten year old asks you for the solution. If you can explain it to a ten year old, then it means you understood.
Without doing all this, solving a question adds absolutely NO value. That is why people wonder why they fared poorly despite the SUPER LARGE number of questions they solved.
Regards,
Amrith