My experience has been that reality testing is initially a great tool to maintain insight and guide my behaviour despite the somewhat compelling beliefs and experiences of clearly audible voices and clear visions.

But there came a time where no rational arguments I could muster were more convincing to me than the experiences I was having. I moved to a point of having one foot in reality and the other in a different world. As I got worse, the world others called reality became a faded grey and the alternative world became boldly more real to me.

I was so convinced by the experiences pdocs call delusions and hallucinations, that I couldn't trust the pdoc or hospital staff because I knew they were part of the plot to destroy me. Logical evidence couldn't be comprehended because I couldn't think coherently. I couldn't read, write or explain what I was going through. It was just plain pain and terror.

Once the antipsychotics had brought me (mostly) back to a state where I could comprehend what was going on, reality testing became a reachable tool again.