Professional Video Game Usability

I've just been reading a thread on The Chaos Engine (TCE) from 2006, where someone asked how many development studios employ usability testing. TCE has private, semi-anonymous forums only for people who are in the games industry so you probably won't be able to read the thread unfortunately.

There were 8 replies from 7 unique users. Only 3 employed usability testing but all reported that it improved their process and they would recommend it to others.