^ OK, that makes sense.
So, for example, I think you're saying that when a manufacturer specs out a device at 5.4W, the 5.4W number includes whatever losses have occurred between the battery and the device, such as through heat rejection or just that you don't get as many mah out of the battery as you put into it during a charge cycle. So in doing a run-time calculation, you wouldn't need to put in any compensation for these inefficiencies. Right?