Both mine hike and were neutered at 5 and 7 months. I think it's dominance, I started a thread asking a similar question. I think my second dog learned leg lifting from his older brother, even though he was neutered at 5 months. I'm not sure the age of neutering mattered in my case
I use belly bands sometimes. If they mark, it goes into the poise pad (for the person that was asking what happend if they potty in it.