Around Summer, locksmiths will notice a rise in certain types of jobs including screen door locks and windows requiring keys or repair. In the case of window locks, more often than not they are actually all on the same key. It is often way cheaper to have a locksmith make a key to your locks than replace all of them. I did exactly this today for a customer in Greenwich, on the North Shore of Sydney. The customer was happy with the price and the time it took me to create a key and cut some extra copies.