You should always try to keep at least two active pairs of running shoes available, if not three or four pairs. Whenever possible, you should avoid running in the same pair of shoes more than once a day, and would preferably not wear the same shoes two days in a row.
When you run in a pair of shoes, even on a warm or cool day with no precipitation and a dry surface, your shoes still get a little wet. Your feet sweat, and the fabric can absorb some of the humidity from the air. By not wearing your shoes two days in a row, you will allow your shoes to completely dry out.
Not wearing the same shoes two days in a row also means that the rubber in the sole of the shoe will have an opportunity to decompress before you wear them again. You are applying a lot of force with each foot strike, and the rubber will get a tiny bit denser and take a little bit of time to go back to it’s normal state. If you never allow it to completely get back to it’s normal uncompressed state, then it’s normal state will begin to default to being a little compressed.
Rotating will extend the life of your shoes. First, the shoes will last twice as long on the calendar because you are only wearing them half as often (or less), plus they will last a little more than that because you are taking better care of them.
Using a different pair of shoes each day is better for your feet as well. You have a better chance of avoiding the start of a run with wet feet, and your feet will not have the exact same cushioning and padding for each run. Doing the exact same thing day in and day out can be detrimental to your body in any type of exercise, so changing things up on a regular basis will help develop your muscles and support a little better.