Esther,

A lot depends on the brand as well. I use to have the same problem. Even with proper brushing I would wear my shoes out in just a few weeks no matter what brand I tried. Then I tried amysafter5.com shoes and they worked great for me. They last a long time but are still flexible and comfortable. They are a fairly new brand but I find them to be more comfortable and made of better materials then even the top brands. And they are 1/2 the price of the top brands! (About $70) I defiantly recommend giving them a try.