It may seem unusual, but for centuries towns and villages shared communal ovens. The baker would stoke a huge fire to bake bread for sale. When the bread was done, then oven would slowly cool for hours. These cooling hours were of little use to the baker, but for a casserole or a roast they are ideal and essentially free.
The grill should be considered in the same way. Why build a fire and not use all of it? Different foods naturally cook better at different temperatures, and with good planning you can make them most of your grill’s energy. (Also, more grilling time means more drinking outside time, which is the reason many of us grill to begin with.)