Sorry to take so long getting back, Charmion. We use an external digital thermometer but I see no reason for the integrated unit in your oven not to work.

We put the probe into the breast in the middle of the meat as it seems to give consistent readings.

By observation, we have figured out why stopping the cooking at a few degrees before it's officially done works well. The temperature in the outer meat is hotter and averages itself with the temperature in the middle of the meat. If you bring the core temperature to the officially declared "done temperature," it is overcooked and dry.

Check the thermometer calibration by using water at several known temperatures. Most likely it's accurate but it's nice to be sure. Trust but verify.

We did a prime rib in the oven this weekend and put several potatoes in the roasting pan, where they could pick up some of the flavor. A few onions went in, too. When the meat was done, we pulled the potatoes and onions. We pulled the skins off and mashed them with chopped up onions, added eggs and made potato pancakes [latkes]. Delicious! The texture is different from latkes made with shredded potatoes but, when fully cooked, is quite acceptable.