Very different in Cambridge. Collaborating on math problem sets was viewed as essentially cheating. If you couldn’t do one or more of the problems then your weekly supervisions were intended to help you along the way to figuring out the answer. Hence the interview format.
And relatively little choice in courses (almost none in the first year, limited in year two), hardly anyone would even think about doing a course from a subsequent year:
“Most students will find that there is enough mathematics in Part IA to keep them busy (or very busy!),
and the Faculty places no expectations on students beyond keeping up with the first-year lectures, examples sheets and supervisions. Indeed there are many other educational and recreational opportunities to enjoy at university, though mathematics itself can hopefully be recreational.
For those who do want something extra or something a bit different from the mathematics in Part IA,
the first choice should be the many excellent lectures provided by the student mathematics societies.”
https://www.maths.cam.ac.uk/undergrad/course/coursesIA.pdf
(I find it quite hard to imagine a US course guide saying “mathematics itself can hopefully be recreational”)