For a number of years I tested all my students with the grammar test above on course entry. I also used vocabulary tests, and I interviewed each and every student, and I asked them to define their own goals in concrete terms. It was then my duty to push them on if they did not progress in accordance with the plan. Yes, there were deviations. In a few instances students 'prepared' for the tests.
Some students are more communicative than grammar-minded.
Some learners have studied grammar for years, but they have practically no experience of oral communication. Some adult students are 'rusty'. Target marks sometimes have to be adjusted, and I make an effort of being aware of this all the time. One advantage with target-oriented education is that there are no 'surprise' marks at the end of the course. Many countries have national normative tests in English.