are shoe companies trying to make more money by convincing us we need to alternate shoes every day? i dont believe that letting the foam decompress is the reason. if i were to run 5 miles today and then 5 miles tomorrow in the same shoe they say thats bad but running 10 miles in that same shoe in one day isnt bad even though the foam is being compressed the same amount if not it is better the first way because according to their logic 'the midsole has time to recover'. do these people not do doubles? they would need a warehouse full of shoes to keep up with all of these runs and the different shoes you would need for each to 'prevent injury'. also, some say its because your body would get used to running in the same shoe and landing in the same way which would cause imbalances and overuse injuries. humans used to run without shoes everyday so you could say that they were getting used to running a certain/specific way and using the same muscles and landing/running the same way all the time too. im not saying i dont believe in having multiple shoes. i agree with that. i have different shoes for different things. easy day, workouts, races, different surfaces etc. but why do you need multiple shoes for the same purpose. lets say you have two easy days coming up. same type of runs, why not use the same shoe?