I personally wouldn't see this as common, especially if you were able to do this from the very start. Most beginners can't really control much, and most experienced lucid dreamers can control quite a bit. I personally am not a beginner, but I'm not quite experienced either. I can control a lot like changing the scenery and what not, but I can't control dream characters. In fact my dream characters are pretty unstable(They morph a lot and I can't seem to stop it from happening). Personally, it makes sense though. I mean, Lucid dreaming is simply being aware your in a dream, thus allowing you to access your subconscious and control the dream. It makes sense that you can control everything in it, when everything is... well basically inside your mind. I think your average lucid dreamer can only accomplish 100% control over everything after a whole lot of practice though, but I can only speak for myself and what I've read in my research. It's cool to hear how much control you have (: If you ever have time, could you maybe share some of your dreams?
"For a Dreamer, Night's The Only Time of Day."