Never run out of propane again!
If you have 2 propane tanks this simple process can help to ensure you never run out of propane again! Probably best to just start with 2 filled tanks. Use only 1 tank at a time. Say you start with the one on the left. You could mark them somehow to keep track if that helps you. As soon as that tank empties you of course switch to the right or another tank to use. Go fill up the empty left tank, but do not use it until the right tank you are using becomes empty. Then switch back to the left tank you filled and go right away and fill the empty.
Don’t forget to bleed the lines of air after switching tanks by running your propane stove top burners.