A first heat-treating method involves monitoring at least one thermal efficiency parameter associated with an irradiance system configured to produce an irradiance flash incident on a surface of a workpiece, and automatically updating control information used by the irradiance system to produce the irradiance flash, in response to the monitoring of the thermal efficiency parameter. A second method involves predicting a heating effect of an irradiance flash to be incident upon a surface of a workpiece, in response to a measurement of a heating parameter of the surface, and pre-adjusting the irradiance flash, in response to the predicted heating effect. A third method involves measuring a temperature of a surface of a workpiece during an initial portion of an irradiance flash incident on the surface, and controlling a power of a remaining portion of the irradiance flash, in response to the temperature.