Both Hefner and Buddha are neutered but when Buddha is here they will both mark and my daughter says Buddha marks at her house all the time so she keeps a bellyband on him when she cannot watch him closely.
Hefner goes on the pads 99% of the time.
Even my 5 year old neutered standard poddle will pee over the yorkie pee on the pads.
I don't think neutering prevents marking in all dogs. I just think it lessens it a little.