With previous dogs, I fed them twice a day. This seemed to ward off begging for human food. There is nothing worse than a dog following you around hounding you all day for food scraps.
Misha has to be fed three times a day. She's had a little trouble putting on weight because of her high energy. I feed her two regular meals and small meal at lunch. She doesn't get people food though.
I think this can vary by dog. My brother has a medium size dog who seems perfectly happy getting one serving of food a day and then eating it throughout the day. I have never owned a dog that doesn't devour her food in less than a minute.