學英語必知：千萬不要浪費時間學文法by Avenging Dark
To date, no one has figured out whether grammar study is necessary or not. There is no point comparing learning a foreign language to 'acquiring' a native language. The reason is simple - you are not a baby anymore. You care about mistakes you make and you no longer absorb a language like a sponge.
Based on my observation, after learning the very basic grammar rules and the 300 most frequently used words (i.e. the intermediate level), learners should let go of memorization and start listening and reading intensively.
Agree that grammar doesn't work. Listen listen listen, and read, then good English will come to you.