New Shoe Paradox

To know whether a new pair of shoes really fits and won't give you blisters, you have to spend a week trying to break them in. If the week-long experiment fails and the shoes really don't fit, you can't return them. So you have to do a good job at the store seeing if they really fit. But you won't really know how they fare over the space of a mile until you walk at least a mile in them. Unless the shoe store has a treadmill section, you have to purchase the shoes and "wear them out" of doors. Is it possible to solve this conundrum? Even my favorite, comfiest shoes had minor issues until I broke them in, so I still took a gamble at the store.