They bust anyone at any time if they feel like it
doesn't matter if theyre ndependent or not.
in mpls they don't require a license for massage but they do go after parlors or groups of ladies more only because there's more money and media attention in it for them.
True independents don't have tons of traffic going in and out of their Incall so neighbors don't complain (it takes a substantial amount of complaints before they'd even investigate)
rarely hear about an independent getting busted unless she's in an area that does require a license  and she's straight up escorting at the same time. I think last time I've even heard anything had to be 5 yrs ago. but charges were dismissed.