My house was built in the 1930's. This means knob-and-tube wiring, and with the creative modifications of the prior owners on top of Depression-era field-expedient solutions one can never take for granted the path taken by any given circuit. In addition, there appears to have been some pruning *not* done at the circuit breaker end of things, resulting in some orphan circuits that still have a label like they are doing something useful. Prior owners all dead or gaga, nobody took notes, so one is reduced to electrical archaeology to discover the truth. I am (slowly) modernizing the wiring, one room at a time. I needed some open circuits in the breaker to do this. So, I called up some friends, dug out multiple strands of Christmas tree lights and anything else that could be plugged in for light, and we played "Circuit-Breaker Bingo" as I flipped breakers and people yelled out if their watch station lights had gone out. A good time was had by all, and I discovered that a) my kitchen outlets and lights are served by three circuits, and b) the entire upstairs (four rooms) was served by *one*.
I'm sure it made sense at the time.