Walks are like tv/internet for you dog. He is mostly stimulated / entertained by smells, which he can get many different ones even on the same walk (like different chanels on the tv). He spend his whole day in the same place (same tv channel) and the walk is the one time he has to be happy.
Please take your dogs out and take your time, it's not only about poop and exercise it's also about mental health for the dog