I also vote "actually, I've become more patient being poly than I was when mono."
I think it is because... well, it has come to my attention that in mono dating, it is apparently acceptable to date more than one person until exclusivity is asked for and agreed to. That has not been my experience. It was my understanding that one does not ask another on a first date unless they are willing to be exclusive from the beginning.
Anyway, as a mono, I always felt as though I was looking for "the one that is meant for me," and the moment I figured out that a woman wasn't my perfect match, I was done. Because, if she wasn't "The One," I was wasting time and closing myself off to the possibility of meeting "The One." Now, I no longer have that feeling. A girl that I'm seeing doesn't have to be "The One," and I'm not missing out on anything by continuing to be involved with someone who isn't "perfect for me." It doesn't matter, as long as I enjoy the relationships I have despite their imperfections.
Also, I'm more open to different types of relationships. None of the women I'm seeing now fit what my description of what I thought, as a mono, a girlfriend "should be." Now, I focus on what I like about the relationships, rather than focusing on what more I'd like.