How do I determine the timing for low-temperature cooking (LTC) for a roast?

Heat the oven to 425°F (220°C) and roast the meat for 15 minutes. This will render the fat and brown the meat beautifully. Then lower the temperature to 300°F or 325°F and roast until the meat reaches the target internal temperature. 

I have learned that it was best to cook the meat to a temperature below the target serving temperature because it would continue cooking during the high heat searing phase. Use a meat probe or a reliable instant read thermometer.