> warming up 2 packs of something seems to use less than double the amount of time for 1 This makes sense. When you see a microwave rated as 750 W, that's assu

> warming up 2 packs of something seems to use less than double the amount of time for 1 This makes sense. When you see a microwave rated as 750 W, that's assuming there is a sufficient load inside the oven that can absorb all that RF energy. Usually there's not, maybe your food can just absorb 400 W, and when you double the amount of food maybe it can absorb 600 W. Mainly this is because the outer ~3 cm of food is what absorbs RF energy, heating of the rest of the food is through thermal conduction.