Look at this example. I understand the reasoning here, in order to save energy one only needs to boil water slightly. But doesn't it also take longer time to boil it the same amount? I'm pretty sure in a given number of minutes, the spagetti will be more ready (more cooked) if it has been boiled more then if it's only been slightly boiled. What do you think? Is there some other factor that could be taken into consideration here?