Readers are told that Miles tends to have jobs in the carpentry trade. For him personally, his job is useful, because he can get a carpentry job just about anywhere. He and the rest of the Tucks are forced to move every ten years or so, because they are immortal. Carpentry skills are needed everywhere, so Miles can easily move, hide his immortality, and find work.
His skills benefit the Tuck family once Mae Tuck is put in jail. She is likely to be executed for killing the man in the yellow suit. Of course the execution won't work on Mae, so the Tucks have to break her out of jail in order to keep their secret. Miles's plan is to remove the jail window, bars and all, in order to free Mae. For a skilled carpenter, removing a window is an easy job. The plan works, and Mae is able to escape the jail. She and the Tuck family are then able to safely leave the area.