I have three dogs and they all happen to be huge. Having two English Mastiffs and a German Shepard, it makes it hard to take them out all at once. If I were to take them out together, I would end up losing all three of them easily. I've tried taking two at a time and I ended up being dragged throughout the walk due to their strength.
What I usually do for walks is take one dog out a day. My dogs are on rotational walks, but that doesn't mean they won't get exercise every day. I try to go outside once a day and play fetch with the three of them. I'm lucky to have a big yard for them to run and play in. I think if you were to rotate the dogs, giving one to two of them a walk a day you should be fine.
