I travel to Poland every year for about 3 weeks, because I enjoy practicing my Polish
What kind of progress do you make with every stay of yours? Is it only "practicing" things you had learned before a visit or are you able to learn new things as well?
It is actually hard to learn new things without being totally immersed which means living in the foreign country and not only visiting it for a relatively short period of time. Thus, in my view, such a stay would mostly mean practicing things that you have already learned.