There are many reasons for a dog to need a visit during the day and I have had to deal with most of them over the years.
New puppies, messy, inquisitive and destructive, they can can get themselves into all sorts of situations, some maybe dangerous to themselves. With a visit I can make sure they are safe, clean up any mess they may have made and help prevent further damage. Even if they are too young for walks, a run around the yard will help use up some of that excess energy so they are more relaxed when you arrive home.
Unwell or dogs recovering from injury, I can check dressings, make sure they are comfortable, clean up any mess if they are immobile or let them out if they are resticted by a medical device. I have had sick dogs and know the worry of leaving them alone all day, so I will email or text you to let you know how they are doing to give you piece of mnd.
Senior dogs. My dog who I brought to America with me is 16 and half years old and I know that although the soul is willing the joints are no longer up to long or fast walks, so short slow walks are the order of the day and I would not mix young energetic dogs with old ones. My walks will be tailored for the ability of the dog. If the dog is not up to walking any distance then a bit of company and attention in the home or yard will break up the dogs day when otherwise they would sleep all day and be restless when you are trying to relax and unwind.