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.