Or have you ever returned a hitch hiker to the person that started it??
I have a friend that carves wonderful little stamps, but who doesn't have much time to go out and actually letterbox.
I offered to place a hitch hiker for her (one of her stamps), but...it seems kind of pointless if she can't eventually get the little book back. Ya know?
How often do you think they get returned?
Is there another way she could participate without having to go out searching??