Main purpose for the rotation would be to give the student a "feel" for that type of setting in order for them to make an educated choice for their future. It takes a long time to be functional and useful at the place you rotate... and there just isn't enough time in rotation year to do that. There are some countries that only do two rotations, one retail and one hospital for 6 months each in Germany, for example. Yes, you can learn the setting where you are in a lot more depth, but overall I think it is far less useful for professional development. You will see once you go through them... everyone gets out of rotations what they want and what they put in. Nothing more, nothing less.