Leaving Sold boards out !

‘Leaving SOLD boards out is good advertising’.  Not necessarily, our records show that the longer a board is left, after having SOLD put on it, the more chance is that it will not be there when we go to pick it up.  Even if it is there it’s more than likely by the bins, behind the garage or in the skip if they have builders in.  Was it worth a £15 board and post in advertising?