A high quality pair of road shoes can in theory last for a very long time. I actually have 3 pairs in rotation, 2 of which are identical models and 1 pair is a higher spec, stiffer and more breathable. There comes a point where they just get stale and smelly from all the accumulated sweat cycles. For me that’s usually after 3 or 4 years and often by then there are some newer models to consider. They don’t actually seem to wear out much at all. I ride flat MTB shoes (FiveTens) and those seem to last me a few seasons too, although they do a lot less mileage than my road shoes.