My artist has done my sleeves and my legs, but I occasionally go and get a tattoo from someone else. I love his style, and I want him to finish what he started on my sleeves, but I like fill-ins from others. Just depends on what you want.
I personally prefer going to different artists,
unless you want to build on a themed sleeve,etc,etc
yes there is a lot of good talent in so cal,
it all depends on what style you are interested in getting,