Page 98 - Turkey Book from Meathead

To hit the target temperature you have to remove the bird from the heat when it is 5 to 10°F below target because cooking can continue for 20 minutes or so after you remove the bird from the heat. This “carryover” cooking can take a perfectly juicy chicken or turkey breast and turn it to cardboard.
Here's how carryover works: Energy cooks the outside of the food. Then the outside of the food cooks the inside of the food by conduction. When we remove the meat from the heat, it continues to cook because some of the heat built up in the outer layers of the meat continues to be passed towards the center while some of it bleeds o into the atmosphere.
So it’s best to remove the bird at 155°F in the breast and 160 to 165°F in the thighs to allow for 5°F carry-over. It will be