I've done this for years as a way to keep my body in balance. I'm not very good shooting left-handed, but I like the feeling of doing it. I've taught myself things shooting left-handed that have helped my right-handed shooting. For example, since my left side isn't as strong as my right side, I found that I was getting the shakes before holding as long as I wanted to, but if I closed up my stance, I was stronger. I applied the same reasoning to my right side, and my groups tightened up.