Coincidence with a capital C

Neither of my oven lamps came on this evening. I immediately thought there was something wrong with the oven circuitry because I replaced the right bulb just a day earlier.

I took the right lamp cover off and screwed in a regular bulb, which worked. Yay! I removed the left cover and tried to unscrew the bulb but only the bulb came out, with the base staying in the socket. The left bulb was awkward to get to, so I had to remove the oven door and unwind the metal lamp base with longnose pliers. A regular bulb lit up when screwed in, so both bulbs had decided to croak at exactly the same time. Then a little bit of fun reinstalling the door. Curiously, the left bulb lasted years; the right one only a day. Same brands, too.

Some of the original work on predicting life of products was done by a guy at GE (I don't remember his name right now) around 1940. He worked with light bulbs, predicting how long it would take them to blow out, and came up with an exponential equation that has been found useful in many places. Even predicting fatigue life of jet engine compressor blades. However, the underlying data is expected to be random. Some nominally identical items fail soon, others later.
So when you buy a "750 hour life" light bulb, that's based on the mean time to failure. No guarantee about your particular bulb. Or jet engine fan blade.

That's how it goes. All the luck went to Fire Station #6, which has the Centennial Bulb -- burning nearly continuously since 1901.