I don't know. I'm not sure the historians fully know. This concept might even be apocryphal to an extent. What I have learned is that the concept evolved (like so much cooking does) from what I described into a "it's actually now a recipe that people prepare once."

Something else I learned is that back in the day, people had different expectations for food quality. We would regularly eat rancid meat (many BBQ sauces were specifically built to hide/safen up rancid meat). And maybe while the concept was "it's always going", there were practical things we like to exclude from oral/written tradition, such as "well... actually we purge it once a week otherwise it goes completely bad." Who knows!