1, can improve self-confidence, sometimes you can't do the exam questions because you don't have self-confidence or your mentality is not well adjusted. If you see too many problems, you are not afraid.
2, can broaden the mathematical thinking, if you only do simple questions, ideas, patterns, routines are fixed, as long as the topic is slightly changed, you can't do it.
3, you can cultivate mathematical literacy, mathematical thinking, every time you do a problem, you should think more and think more. Don't just pay attention to how many questions you have done. Some good questions should be done repeatedly, repeatedly trying to figure out the ideas of the questioner, thinking about mathematical problems, and paying attention to mathematical thinking and mathematical literacy. This is the core of learning mathematics. That's all that matters.
You can keep asking questions.
Mathematical thinking does not pay attention to training now. But it's important. People who are good at mathematics in high school are all people with good mathematical literacy and thinking. Junior high school is the same. If you can train well in junior high school, it will be very beneficial to the senior high school entrance examination and the college entrance examination.