I went to a university that I thought was like this across the board...most of our psets were collaborative and took days of working together, plenty of open book tests or cheat sheets allowed because it wasn't the formulas themselves that were important, it was the concepts. I never thought twice about all of us working together because it was actually encouraged and just blindly copying others' work was a dumb thing to do since exams were such huge portion of most of the grades.

Junior year, I got an email from my professor the morning of the final exam saying that I had received zeros on a pset and would fail the class because my code to produce the model that answered the question was the same as the group I had worked with. We had all put all of our names on the code that we all separately submitted, because the code wasn't the point at all...just the model itself.

Anyways ended up being this huge thing, and actually my professor had committed several violations by sending us that email the morning of the final exam. He ended up apologizing in the end...I'm sure he was just acting blindly on a TA's insistence. I still think about how bizarre it was almost 15 years later - never had an issue collaborating on work outside of exams or essays with any other class, but it did make me a little scared to work with others after that.