This is a bit of a misterpretation. Yes they make that calculation but to know how to adjust the age of retirement and because there are shunt laws that limit the expenditure to a given percentage of gdp.

Portugal(p in pigs) is such a country and this shunt law is a 2/3 law meaning if debt ceilings are overridden by government or parliament it will be struck down by the constitutional court. just recently there was such a law and it was promptly sent there. E