i think it's definitely true that in smaller, more close-knit colleges people get to know each other better. in brasenose, for example, all of the freshers and most of the 3rd and 4th years essentially live in 2 quads, and so everyone is so close to everyone and you inevitably end up bumping into people more often. i showed a friend around brasenose who was thinking of applying, and she said that in other colleges it didn't seem as close knit, and when people showed her around they didn't know many of the people whereas i know most of the people i'd say, certainly almost everyone in 1st year.