[Dan Evans]

And yet for some reason, the cheap halogen lamp my wife bought in 1994 is still burning in our den---on it's original bulb.

The life of an incandescent bulb varies a lot with line voltage. If you dim a bulb slightly it might last ten times as long although efficiency suffers.

[Old Professer]

Very good point, here in Nashville we have relativly high line voltsge - I routinely measure 127.5VAC; I tried 130V lamps but they are too dim for good illumination except as hard to access fixtures where changing them is a greater inconvenience.