We have a neighbor that built a larger fenced in area for her dog, tucked a bit away from the house. She did it to allow more exercise for her beagle. I told her when she was planning it that if you aren't there with the dog all it will do is sit by the gate and wait to be taken back toward the house, or at least on a walk with the owner. That's all the dog does, she does not use the enclosure for anything now.
Just saying, a fenced in yard may well contain the dog, but they want to be with the family, for the most part. Unless someone is there with the dog I wouldn't expect much exercise.