Talking with my T helps me to notice when I am making assumptions or jumping to conclusions, or my thinking is distorted in some way. I think these are hard things to realize without another person's help. In general I think it helps to have another person to challenge my perspective, otherwise (like many people) I tend to confirm my own biases and preconceived ideas, even if I'm trying not to.
My T also encourages me to spend time talking about emotions, ideas, fantasies, etc. that I tend to shut down because I think they are uncomfortable or unrealistic. This helps me to understand how I really feel about things and consequently to live in a way that is more honest and generally makes me happier.