Most people recommend replacing shoes every 300-500 miles, but it really depends on the person. For example, a 200 lb person is going to put more stress on a shoe over 500 miles than a 100 lb person, so they should probably replace it sooner, all else being equal. Another thing to look for is if the carbon rubber outsole is starting to get worn, the softer midsole is probably trashed and not doing its job protecting your feet as well as it should.
Most people recommend replacing shoes every 300-500 miles, but it really depends on the person. For example, a 200 lb person is going to put more stress on a shoe over 500 miles than a 100 lb person, so they should probably replace it sooner, all else being equal. Another thing to look for is if the carbon rubber outsole is starting to get worn, the softer midsole is probably trashed and not doing its job protecting your feet as well as it should.