If you buy long baguette but cannot finish it in 3 days, it will harden like a rock.
On the 3rd or 4th day, keep the remaining baguette in the freezer to prolong it for another week. When eating then take it out, cut into small tranches of 3″ to 4″, slice horizontally half (don’t cut thru to break it half), drop 1 ~2 teaspoons of room-temperature water in it, place in a toaster (or oven) for 5 mins. Voilà the baguette is again as crispy as fresh before.
The effect of freezer is to lock the moisture in the baguette. Few drops of water is to replenish water lost.