When a lord had a castle but did not reside there, a Jodai-garo (Karo in charge of the castle) was installed, but when a lord resided in a castle or jinya (his regional government office), naturally jodai-garo were not installed.
主君が城主以上のときは城代家老も置かれたが、主君が城主大名や、陣屋のときは、城代家老は、当然に設置されなかった。