For the Ag Leader Integra, the correct way to calibrate is to run 4-6 loads, each load weighing between 3000-6000 lbs, and each load ran at either a different speed or different cut width.  The idea is to have each load represent a different crop flow rate across the sensor.    Done correctly, and with accurate scales, you can easily get it within 2% error, and many times less than 1% error.

For the new InCommand displays, there is a new calibration option, which will allow you to calibrate with 2 or more loads and still maintain the same accuracy as previous Ag Leader yield monitors.