"Kyle" wrote in message
So
when I run out at 10:00 at night in the middle of playing cards, I can
get a fresh tank without having to deal with the surly gas station
attendant down the street.


That is why you have a spare. No running to the store at 10:00 PM. Everyone
has different priorities. I'd rather save the $5 to $10 per tank and have
my tank re-filled.