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Your voltage and vibration causes for unusually short incandescent bulb
life are correct; but heat and on/off cycles are not. The little bit of
extra heat in a tight fixture makes no difference to a bulb filament which
is operating at 3373 degrees C. For heat to affect bulb life, you have to
either have enough heat to melt the glass, crack the internal glass seal
or destroy the lamp basing cement. Think about incandescent bulbs in
ovens and other high-temperature applications. There's nothing special
about them.

On/off operation might affect bulb life a bit when the bulb is old; but
not when the bulb is new. If on/off made a difference, we wouldn't see
flashing sign lamps on theater marquees.

....but a bulb that is never shut off will last longer than a bulb going off
and on. All my bulbs fail when turned on.

If a bulb is never cycled, its filament can get much weaker before it fails
because it doesn't have to withstand any shock of heating or cooling.