Running vacuum tube without grid or bias voltage
Perhaps they're talking about indirect-heated cathode-oxide degrading?  See what they say about the failure mechanism.

In common audio/radio tubes, "degrading" means the oxide gets contaminated, not that the filament breaks.  Yellow-glowing, direct-heated filaments are not commonly encountered in tube circuitry.

In any case, if you run a tungsten filament at 99% of rated voltage (or 95%, or 90%,) the expected lifetime becomes huuuuuuuge!   Simple: un-tape the filament transformer winding and pull off a couple feet of secondary wire.

Heh, after I'd done that just once, I realized that transformers ...they have user-servicable parts inside!  You'll never leave your transformers alone any more.   Also you can dip transformers in polyester resin or hot wax to greatly increase isolation voltage of floating windings (even pull a temporary vacuum to clear out any air bubbles.  Who says that vacuum-impregnation was complicated?!)  Also,  'tune' your 2watt carbon resistors with a triangle file.

Also Vaporizing cities with radio, 1947, no tubes in sight!  "Krakatit," Karel Capek