A very confident dog will pee every 9 feet, to let everyone know he's around and the GREATEST.

A not-so-confident, or young dog, will often wait until he gets home, hoping that if he doesn't leave any "pee-mail" when he's out and about, nobody will notice him

When you come in from walks, hang around the garden for a bit. Have a brolly and a book with you if it seems like it might take a while