My understanding is that the interval testing, and number of tests, varies somewhat depending on how likely that they believe the contact may become positive. ie Household contacts can be given more frequent testing.
Plus also it depends on the risk to others. For example in the apartment building as there is some risk of transmission between apartments (as in HQ) if they only test just before release that could with a late case mean that all residents would have their quarantine clock reset by another 14 days. Whereas if people are in detached dwellings (houses) there is no risk of extending a neighbour's quarantine period.
I understand too that at present all positive case are removed from the apartment building, and that on the last positive case all the remaining residents quarantine clocks were reset to 14 days.