from an ESOL instructor practising in the US:
Learning a language is a bit like being in a small boat on a body of water. When students first begin learning a language, it's a bit like being in a small boat that is passing midway down a narrow stream. As the boat moves forward, the banks of the stream are passing by, so it is easy for the learner/traveller to have a sense of progress, and a sense of where they are going.

When you become an advanced student, however, you have a problem -- the small stream has opened up into an "ocean." There are no "banks of the stream" anymore; nothing to give you a reference point or a sense of direction. The language you've learned is now an ocean. It goes on forever, and you can move and see in any possible direction. It is now very difficult to have a sense of progress or a sense of direction. You can move your boat over to the region of legalisms and legal English, for example, and study those for a while...but when you finish, there is still something else to learn. And there always will be.
So what do advanced learners do? They have to develop new tools to give themselves a reference point and be able to determine where they are going and how they are progressing. They need a "nautical chart": a set of explicit goals, means to achieve those goals, and ways or milestones to measure your progress. Then we go through an exercise where the students have to develop five very explicit, specific goals for language acquisition, and how they will achieve those goals. For example, one student decided she wanted to learn the names of all the Italian spices, and what dishes they are used in.