I have a Saturn/SN conjunction natally. I wouldn't say that it blocks evolution, but it seems to sometimes make me work on some unpaid debts from the past. My ex-wife of about 7-11 years has a Mars/Saturn conjunction in the same spot, so we had a Saturn/Saturn/SN/Mars conjunction. I do not know if it was a good or a bad relationship, some was good and some was not so much. It was the longest relationship for both of us. The relationship was quite evolving though for both of us, and perhaps even more so after it ended. Actually, one of the reasons I wanted to end it was that we stopped evolving, and I didn't like it. Perhaps we learned that Saturn's lesson and the lesson was over for us. We are still friends though and do not regret anything.