When I'm making things, especially to fill an order, I usually make a few extra just in case. I've been in situations where I've made just enough and then something happens and I'm short. So nowadays, I make a few extra just in case.
I have a drawer that's filled with the pieces that are not perfect. It's true that all of my pieces have little hallmarks of the human hand, tiny nicks and dings and fingerprints, but some have more than others and I pull those. I don't want a customer to question the quality if they got one that was defective. So I keep the broken ones. And I have to admit, sometimes they're my favorite. I never sell them, but I keep them and mend them and make them whole again.
In Japan, they have a method called, "kintsugi". It's also called, "kintsukuroi". It's a technique of repairing broken pottery and ceramics with a lacquer mixed with gold. Instead of discarding or hiding a broken piece, it celebrates them and elevates them.
For instance, I recently made a bunch of these bronze coins. Sometimes when I'm pressing them out, there are certain areas that are thinner than others. And sometimes in the firing process, the area is so thin that it burns away and leaves a little fissure. I can't sell them like that, so I keep them.
I keep them for a rainy day, when I have time to sit down with them and see how I can help. Usually things hang around a long while before I get back to them. I so rarely have free time and sometimes the fixes are easy and sometimes they're more involved. So that drawer is awfully full.