Good Heavens! That is quite a rate of attrition. My last shoes (Shimano - Iace up but I'm not sure of the model no) lasted somewhere in the region of 12-15 years. In fact they're still usable so I've hung on to them for emergency use - such as when I've ridden through an unexpected cloudburst with my regular shoes and they haven't yet dried out. Mind you, I don't do a lot of walking in them.