Gracie walks 1.25 miles almost every day. She would stop and refuse to go on at times last summer when she was still a puppy. It was also hot! I carried her home many a day.
Now she's used to it. Sometimes she take's her time....stopping to potty a lot to get Daddy to give her a treat....or to sniff the street....or pursue a person, etc.
Other than that, only very wet or cold conditions cause her to try to turn around and head home.