Ideally, a government would quarantine all probable cases with the aim of extinguishing the disease.
But if the disease is spread enough (inside or outside your borders) so that is impossible, the next best thing is to reduce social interaction just before your health system collapses, and just enough to avoid a collapse. That minimizes both the cost and time of isolation.
But if the disease is spread enough (inside or outside your borders) so that is impossible, the next best thing is to reduce social interaction just before your health system collapses, and just enough to avoid a collapse. That minimizes both the cost and time of isolation.