This is going to be a witty topic!
I can only speak for the very posh Cherwell Mansions part of the accomodation, but no such rule appeared in force when I was there.
Just check out the state of the communal areas on Monday mornings and listen to the cleaners complain. (well worth getting in their good books by the way..to get the latest goss about the place)
Ah... very happy days- I enjoyed living 'on campus' as it were, even if £95 p/w was steep (especially for Cherwell!)
I wouldn't take the rule book too seriously, but bear in mind people are taking flying/ground tests every day. Moderation in everything I guess.