I've always taught year-round other than a couple weeks off at Christmas, when I told the students to just have fun at the piano playing the Christmas songs they had learned, as well as keeping up with technical exercises and scales. In the coming year, I have more breaks scheduled, ie 3 weeks off around the start of school, 4 weeks off at the end of school, and a couple other breaks here and there. What instructions do you give your students to avoid slipping backwards in their skills during breaks?