With a city that has a million citizens, the 65k of individuals is still the cap of people at once on the streets. We have tested this a lot and cities look nice and lively with this number, and it keeps the system requirements decent. And the 65k does not take into account people who are inside a building, so someone can go to work, and while they are inside the workplace, working, they do not take up any room and another citizen can start a journey somewhere. The original worker will not leave for home until there's room, meaning there's less than 65k people traveling. The 65k is not per week, but a number of simultaneously simulated individuals on the streets.
Everyone still exists even when not on the streets, they retain homes, names, workplaces and family relations, you just cannot see the people when they are inside a building.