The period between burnings is cited as 75 years. Why would you clean from pests once in a century? It is better correlated with a lifespan of a human* which mi

The period between burnings is cited as 75 years. Why would you clean from pests once in a century? It is better correlated with a lifespan of a human* which might suggest that they've considered a house to have the same lifespan. * the average lifespan was much shorter but it includes children mortality and once above the age of five a human had a good chance to reach retirement.