KillarneyRose, good to see you back!
Back in the day at MIT, all freshmen and transfers were assigned temporary dorm rooms. They then immediately (almost as soon as they set foot on campus) went into fraternity, sorority, independent living group, and dorm rush. (Most of the independent living groups are coed and local.)
If you signed with a fraternity or ILG, you immediately moved into the house. Freshman accommodations were generally quads, from what I saw, except for one ILG that had a sleeping porch for everyone. If you joined a housed sorority, you stayed in the dorm, as there were more sisters than beds in the houses. If you joined an unhoused sorority, obviously you stayed in the dorm.
You notice I mentioned dorm rush. Freshmen and transfers also got to visit the various dorms on campus and then rank-order them. This happened concurrently with FSILG rush. So unless you KNEW you didn't want to go greek and decided to focus solely on dorm rush, you were pretty busy during those few days! Those people who did go through FSILG rush were also encouraged to go through dorm rush, just in case they didn't get a bid to a fraternity or ILG.
All freshmen were required to live in "campus approved housing", which included dorms and FSILG houses, unless they commuted from their parents' home (which was pretty much unheard of).
Policy has since been changed. Now, all freshmen must live in dorms. I don't know what happens if a sophomore/junior/senior pledges a GLO and wants to move into the house immediately (i.e. if they have to break a contract, pay a fine, etc).