For me what works is not holding at anchor, but maintaining the pull at anchor, big difference. Maintaining the pull with my back primarily and keep a tense free hand, allows me to focus on the target without getting all tense about it. If you are building tension in your shot, you will build up the anxiety, not good. Have you ever watched some of the best shooters, besides great form, they look relaxed not a bunch of nerves ready to explode.