Not fixing worn parts of your shoes in time is very common, which can result in a backlash with a much more expensive repair than necessary. One concrete such example is not replacing the heel top piece in time.
This is something I’ve talked to numerous cobblers about. The fact that customers can often save a lot of money just by getting their shoes in a few months earlier, all too often cobblers get shoes in when it’s “too late”. This can be because, for example, the shoe has been walked on for so long that a hole has opened up in the outsole and moisture has penetrated the cork and insole, damaging the shoe far more than necessary, or because the toe has been worn down to the welt, forcing the cobbler to replace the entire welt rather than just a simple half-resole. The most common mistake people make, however, is to wear down the heel too much.
A heel is made up of several lifts and then at the top piece. This top piece part is either all rubber or leather with the back piece in rubber. It’s only the bottom part that is made to be worn on. The lifts are not always made of the same leather as the sole and heel top piece, but are sometimes made of a cheaper, less hard leather, and sometimes in even of leather board or paper board, which will wear down much quicker. You should simply never let the wear get to the point where you start to wear down the lift pieces. It also costs an additional sum if the shoemaker has to replace also the lifts in the heel, completely unnecessarily. If you notice that the rubber at the back is down to just a couple of millimetres, it’s always cheaper to stop using them and leave them to the cobbler, instead of thinking that “if I wear them for a while longer, I will get more use out of them before I have to pay for a heel replacement”.