The mortgage system we have in the United States--characterized by: domination by the government (in the form of GSEs), long (30 year) fixed rate mortgages with no prepayment penalties, high leverage ratios (up to 19:1 or higher), and low spreads--is not the system used elsewhere. Other countries also tax mortgages and homes differently, and may have far more widespread rent regulations in place.
Rules of thumb and folksy wisdom that was developed in the context of the US system probably won't translate well to a very different one.