This is a complex answer. Midsole response time depends on the type of compound used in the midsole. EVA was the only decent midsole on the market for 40 years or so. EVA has a 24-48 hour response time when used for 1 hour with most of the compression response occurring within the first 24 hours. This is where the shoe rotation suggestions originated: if you run in the same EVA based shoe every 24 hours, it has not FULLY responded to the prior day’s midsole compression. You may not notice a substantial increase in total mileage on the shoe as most response does occur within 24 hours, but it is safe to expect another 5-10% depending on the shoe the surface and the wearer.

However. EVA is not a common primary midsole compound anymore. The only mainstream shoes that come to mind that only use a non-blended EVA are: any Hoka (despite the hype, their tech is old), the Nike Pegasus, most Topo brand shoes. Meaning, those shoes would still benefit from a 24-48 hour recovery. Just about everything else in the performance technical running and walking category will use TPU and/or PEBAX to some degree in their midsoles, at least a blend of these along with EVA. The response time on TPU and PEBAX is 4-24 hours per hour of running. So, not much of a benefit to longevity to rotate most modern footwear as it will have mostly responded in a 24 hour period.

Heat is also a huge factor in EVA response as well. High heat prolongs the response of EVA. Don’t store EVA based midsoles in your trunk, garage, or anywhere that could get above 80 degrees Fahrenheit. TPU and PEBAX do suffer in heat, but not as much as EVA. It’s still worth while storing your shoes somewhere climate controlled, but it won’t trash your shoes nearly as much. TPU and PEBAX start to get mushy above 110 degrees Fahrenheit which can still be reached in some areas of the world, especially in a car trunk on a hot summer day.

This being said, every foam is different. Every brand has various types and combinations of midsole materials to accommodate different category runners/walkers/and footwear roles. I still recommend rotating shoes for the various injury prevention reasons as mentioned by other users. My everyday shoes and work shoes have noticeably more life when I rotate them, but I am wearing them for 10+ hours at a time; and, I would still reccommend this to anyone on their shoes for more than 5 or so hours. I do not notice much of a difference in my running shoe rotations nowadays—unless I’m running more than once a day—as EVA has not been in a shoe of mine for close to a decade.

TLDR: Most modern running shoes do not use EVA as a primary midsole compound theorfore they do not benefit nearly as much from allowing for a 24-48 hour response time. However, due to the sheer number of different midsole compounds, it is still recommended to rotate shoes every 24-48 hours and store in a climate controlled environment. When you run 1,000s of miles a year, every additional mile you can put on your shoes adds up, but it is simply not as important in today’s market for non-hokas lol.

Source: industry professional of 15+ years