Kontrolor,
yes and no : STCA stops either when the conflict is over OR when the machine decides it's too late anyway. That means when the distance between conflicting traffics is already below the minima.
Blockla and Wlatc,
I don't know for USA, but I think now in Europe, as I understand European Control License, the controller must say he's unable to control and the supervisor must find a plan B (find another controller, or implement flow management procedures, or another configuration, or ...).