"Young people in some countries are encouraged to take a year's break between high school and university to work or perhaps travel. This idea has both advantages and disadvantages." "Juvenile" is technically correct but it also has the meaning of "young criminal". "For example" seemed a bit of a clumsy fit, so I cut it and added something smoother. For "proposition"... well, the idea is already in force and well past the proposition (suggestion) stage. It would only be a proposition if it hasn't happened yet.