We placed a box on a little pond in front of my cabin in 1997 and that location has only failed once to attract a nesting woody.
On occasion we have witnessed the box empty out and watch the mother gather the family for a few minutes in the pond then strike out for the creek near the trees.
I have some boxes placed on some trees along the creek, but Screech owls, squirrels and Starlings nest in them more frequently than the woodys.