When we had a pair of siblings, both seemed to wolf down their food, but one was leading the speed. One wanted to be able to eat a little of her food in the moment, and save the rest for later. The other wanted to eat everything available always no matter what. It didn’t matter that we rescued the one’s food after she finished eating, she knew the other one would try to get it so she wolfed her food down too. We fed them in different rooms, and then she was able to slow down (usually wouldn’t even finish, and we’d pull the food bowl up and give it to her the rest later in the day), but he kept wolfing. He was also the runt of the litter when we got him, not sure if that had anything to do with how he responded to food, or if he just had more of an “appetite” than she did and that’s the way they were. The boy was basically inhaling the food. At the time, we just let him be…
The dog we have currently, it depends. He used to scarf it down… He also used to be a stray, and then in a large cage with half a dozen other dogs. He’ll still eat rather quickly when he does eat, chewing just enough to swallow, but if he’s not hungry (which usually means when he hasn’t been run,) then he’ll just leave the food in the bowl—sometimes all day. We got him this treat maze ball for when he’s home alone—give him something to do—and when we’re leaving in the morning will often put his breakfast in the ball for him. Like the food dishes above, it also slows down the eating process.
Basically, I’m just offering first-hand experience that agrees with what people have said above—dogs seem to somewhat naturally eat fast (well, depending on the dog), and they also learn to eat faster/leave nothing behind when they’re around other dogs. In my experience, when they learn that their food won’t be touched, they usually become more relaxed about it… but not always.