As long as he's doing this outside the house, I don't think this is such a big issue. I know, they do this on almost every thing they come across. However, when you take the dog out, that's the time you give to your dog to enjoy himself, whether he enjoys that by sniffing the ground or by peeing.
I don't stop my dog from marking the territory, however I do set out a time for him, let say 10 seconds. I let him sniff for 10 seconds and then say, 'that's it, time to go'. If you practice this technique, this will at least reinforce an idea that whatever he wants to do, he has to do that quickly and that he can't have minutes to sniff the ground. Also, if he tries to pee on any human, simply be assertive and don't let him do so( keep him on leash). He will understand that sonner or latter.
My way of training is that I don't stop my dog from doing certain things that will stop him from BEING A DOG. It'll be unfair to expect from my dog not to bark at other dogs in the park. It'll be also unfair to expect from him not too pee as that's the very right that I've given him to do outside the house. It doesn't matter whether he does it once or twice. As long as he does it outside my house, It doesn't matter to me