Do you think that constantly doing English grammar can help improve English

When i first came to HK i didn't know what grammar was. I had never done any grammar before. But now we have to do them at school. The problem is that every time grammar exercises at school, they seem to confuse me. I have failed in the English exams due to the grammar questions which is around 80% of exam paper. As a non-Chinese speaking person, it is actually very shameful. But if im not wrong, grammar isn't really taught in native English-speaking countries. To me, grammar is based on common sense and fluency. But it seems that the more i do, the more confusing it is. I used to have very good grammar but now it's terrible. I don't believe that grammar exercises are useful for students. I believe that the frequent usage of English is the best way to learn English. My friends who are Chinese believe that reciting grammar is the key, however i find this inflexible. I would like to ask if grammar can have multiple answers to some questions or if there is only one fixed model answer? My teachers say that if my answers aren't exactly the same as the model answer, then i am wrong. But then to me i think its correct. I also think that the HK education system in English should be changed into a more flexible method of teaching grammar rather than just constantly doing grammar exercises. Please also tell me how i can improve my grammar without confusion. Also, please share your opinions!

Your grammar seems fine so I'm not sure what's causing so much distress? There are rules in grammar so you need to understand why the "right answers" are correct. Some questions may be ambiguous and thus have multiple answers, but a properly-constructed question should only have 1 right answer.

Everyone has different ways of learning. Memorising works for some but not for others. Doesn't matter whether you are constantly doing grammar exercises.. What matters is how much you are absorbing from your chosen methods!