Now I am new to this, but it is my understanding/opinion that:
P only to the person who made the stamp and originally planted it.
F counts only once, unless, A. it has changed location B. it is in a
box you havent been to before. I would think you would count it in a
personal maintenance call on one of your boxes. I know that
contadicts but my reasoning is that why would you return to another
box, you know where it is, if you go it would have to be because
someone showed you a new area and you wanted to go back, or check
out any recent visitors. That doesn't count, unless the box moved
changed location, and clues. So unless all that changed you wouldn't
count that box. Hard to pass up a stamp but how could you count it,
I could visit 3 boxes (that I know of everyday without getting in a
car) looking for a HH. Part of the fun of letterboxing is the
mystery so my thought would be leave it there for the next person,
if it is there for a while then maybe think of moving it, but the ?
of does it count as a F would arise again. I dunno, just my opinion,
and it could go back and forth forever, a guideline would be nice!
lol.

dregan (SE PA) P1 F4