[watwut]

In college where I was at last year exams were public knowledge and anyone had access to them. No one seen it as cheating to try last year exam before going on this year.

Yes, it means teachers have to vary tests, but then again it gives you repository of exercises to learn from and to train on. It is just win for learning.

[qwhelan]

This is an explicit rule introduced at the beginning of most Caltech courses, so the norm is that that behavior is cheating due to being warned in advance.