How low do you let your tank get before stopping?

I used to let my fuel go below 1/4 tank if I was sure I could make the next town.

A couple years ago I was headed for Ft Peck Montana. Planned to fuel up there only to find Ft Peck is pretty much a ghost town today with no diesel available.

Had to have Sam Club membership bring me 5 gallons of Disel from Glasgow as I was not sure I could make.

Now I always refuel at 1/2 tank plus my bladder is usually past the 3/4 point by then.