Students were free to do the homework or not, collaborate on it or not, as they saw fit. It was regarded as a learning tool that students could decide how best to make use of for themselves.

I thought it worked rather well, although the high stakes final exams were rather stressful :-)

(Attending lectures was also optional. Institute policy was that attendance would not be taken, and would not be a factor in the grade. You were free to attend lectures or not, do the homework or not, and if you got an A on the final, you got an A for the course. Some students could do that, such as the legendary Hal Finney, but I learned the hard way that I could not afford to miss any lectures and must diligently do and understand all the homework on time.)