I change the chore when it?s too burnt or it becomes clogged. Sometimes I can remove the old chore, pull it out so that you can see the mesh better, and reuse it. That works sometimes. Also, I save old chores that I know have resin in them so when I haven?t bought new stuff I?ll use those and it?s usually good for another 2-3 hits (which is all I need because when I use it like that it?s usually for an early morning shift at work and I gotta be alert.