I'm from California and unfortunately it is true, at least for the younger generations (people between 12-30 years old). I would say that we use "like" more than "you know." However, it's not a strictly Californian thing. For example, I have a friend from South Carolina who constantly uses the word "like" throughout her sentences. Here's an example of something she would say:

So I was like going to the store and like this guy was just like, "The store is closed." Like, it was weird. Like how did he know?