Living in Japan, I can verify that there are two major types of English students here.
Group one learns to speak casually, and often.
Group two can be handed a Shakespeare text and answer any question about it.
Group one will have a completely natural and fluent conversation with any English speaker. They can write casually and be completely understood.
Group two will be able to identify grammatical mistakes on a test. Many are incapable of even rudimentary conversation. These people did well on college exams and are responsible for the horrible, worse-than-machine translations you see on signs and government reports in this country.