Trying to make sure I don't misunderstand this: If your slave goes away from the household for some reason, but has not been sold etc., it still adds 1 to the Ownership counter for each day? So like, a person who's been working in your mansion for a week, and a person who spent 6 of the 7 days out of the rotation due to vacation/recovery/whatever, would have identical numbers added to their variable?
That feels like it's working as it should be. Feels like if the number of days owned were calculated minus "days outside the rotation", it'd wind up with way more problems.