Roast cooking time depends on weight and the target internal temperature, and USDA guidance sets the safe finishing temperature for each meat. Minutes-per-pound guidance verified against USDA guidelines, not a rough guess - though the thermometer, not the clock, is always the real answer.
Minutes-per-pound is a real, useful estimate - but oven accuracy, starting temperature, and the exact shape of what you're cooking all shift the real answer by 15-20% or more in either direction. The US Department of Agriculture is explicit that time is only a guideline: the only way to actually know something is done is to check the internal temperature directly - 165°F in the thickest part for poultry, checked with a real food thermometer, not a pop-up timer, which can be unreliable.
The presets here reflect real, independently-cited minutes-per-pound figures for the two most common holiday roasts, but every oven runs slightly differently. Start checking the temperature about 30-45 minutes before this estimate is up, not exactly when the clock says it should be done.
It depends on the meat and the doneness. Times here are worked from weight and target internal temperature, using USDA safe finishing temperatures - a meat thermometer is more reliable than any time-per-weight rule.
USDA guidance sets 63°C for whole cuts of beef, pork, veal and lamb with a 3 minute rest, and 74°C for all poultry. Ground meats need 71°C.