Old Grad here. I lived in 3 different buildings during my 4 years at West Point due to all of the constructions taking place. After plebe year, I got to choose my roommates, which were the same from Yearling-Firstie. The building they live in depends on which regiment/company they are in. I was fortunate to not have to change companies during my 4 years, but the class of 2018 had to scramble companies twice, meaning they also had to move buildings. Not sure what it's like at school now, but it can vary year to year depending on the leadership.