I pour my tea with the water nicely steaming, but never boiling. I have a feeling that the 45 second rule would be great if you want to reuse the tea leaves for a second cup of tea, but I prefer to leave my tea steeping for at least 5 minutes (sometimes 10 minutes). After that, I remove it, because there isn't much of anything left.
If the water is boiling, it can draw out the bitterness, and "cooks" the leaves as if you were making boiled soup. That's a good approach for roots, bark and stem teas, but leaves and flowers need less heat.